Copy over files from GN3 repository.

55 files changed, 5110 insertions, 0 deletions

diff --git a/gn_auth/auth/__init__.py b/gn_auth/auth/__init__.py
new file mode 100644
index 0000000..a28498d
--- /dev/null
+++ b/gn_auth/auth/__init__.py
@@ -0,0 +1,5 @@
+"""Top-Level `Auth` module"""
+from . import authorisation
+from . import authentication
+
+from .views import oauth2
diff --git a/gn_auth/auth/authentication/__init__.py b/gn_auth/auth/authentication/__init__.py
new file mode 100644
index 0000000..42ceacb
--- /dev/null
+++ b/gn_auth/auth/authentication/__init__.py
@@ -0,0 +1,24 @@
+"""Handle authentication requests"""
+
+import bcrypt
+
+def credentials_in_database(cursor, email: str, password: str) -> bool:
+    """Check whether credentials are in the database."""
+    if len(email.strip()) == 0 or len(password.strip()) == 0:
+        return False
+
+    cursor.execute(
+        ("SELECT "
+         "users.email, user_credentials.password "
+         "FROM users LEFT JOIN user_credentials "
+         "ON users.user_id = user_credentials.user_id "
+         "WHERE users.email = :email"),
+        {"email": email})
+    results = cursor.fetchall()
+    if len(results) == 0:
+        return False
+
+    assert len(results) == 1, "Expected one row."
+    row = results[0]
+    return (email == row[0] and
+            bcrypt.checkpw(password.encode("utf-8"), row[1]))
diff --git a/gn_auth/auth/authentication/exceptions.py b/gn_auth/auth/authentication/exceptions.py
new file mode 100644
index 0000000..c31e691
--- /dev/null
+++ b/gn_auth/auth/authentication/exceptions.py
@@ -0,0 +1,4 @@
+"""Exceptions for authentication"""
+
+class AuthenticationError(Exception):
+    """Base exception class for `gn3.auth.authentication` package."""
diff --git a/gn_auth/auth/authentication/oauth2/__init__.py b/gn_auth/auth/authentication/oauth2/__init__.py
new file mode 100644
index 0000000..e69de29
--- /dev/null
+++ b/gn_auth/auth/authentication/oauth2/__init__.py
diff --git a/gn_auth/auth/authentication/oauth2/endpoints/__init__.py b/gn_auth/auth/authentication/oauth2/endpoints/__init__.py
new file mode 100644
index 0000000..e69de29
--- /dev/null
+++ b/gn_auth/auth/authentication/oauth2/endpoints/__init__.py
diff --git a/gn_auth/auth/authentication/oauth2/endpoints/introspection.py b/gn_auth/auth/authentication/oauth2/endpoints/introspection.py
new file mode 100644
index 0000000..a567363
--- /dev/null
+++ b/gn_auth/auth/authentication/oauth2/endpoints/introspection.py
@@ -0,0 +1,48 @@
+"""Handle introspection of tokens."""
+import datetime
+from urllib.parse import urlparse
+
+from flask import request as flask_request
+from authlib.oauth2.rfc7662 import (
+    IntrospectionEndpoint as _IntrospectionEndpoint)
+
+from gn3.auth.authentication.oauth2.models.oauth2token import OAuth2Token
+
+from .utilities import query_token as _query_token
+
+def get_token_user_sub(token: OAuth2Token) -> str:# pylint: disable=[unused-argument]
+    """
+    Return the token's subject as defined in
+    https://datatracker.ietf.org/doc/html/rfc7519#section-4.1.2
+    """
+    ## For now a dummy return to prevent issues.
+    return "sub"
+
+class IntrospectionEndpoint(_IntrospectionEndpoint):
+    """Introspect token."""
+    def query_token(self, token_string: str, token_type_hint: str):
+        """Query the token."""
+        return _query_token(self, token_string, token_type_hint)
+
+    def introspect_token(self, token: OAuth2Token) -> dict:# pylint: disable=[no-self-use]
+        """Return the introspection information."""
+        url = urlparse(flask_request.url)
+        return {
+            "active": True,
+            "scope": token.get_scope(),
+            "client_id": token.client.client_id,
+            "username": token.user.name,
+            "token_type": token.token_type,
+            "exp": int(token.expires_at.timestamp()),
+            "iat": int(token.issued_at.timestamp()),
+            "nbf": int(
+                (token.issued_at - datetime.timedelta(seconds=120)).timestamp()),
+            # "sub": get_token_user_sub(token),
+            "aud": token.client.client_id,
+            "iss": f"{url.scheme}://{url.netloc}",
+            "jti": token.token_id
+        }
+
+    def check_permission(self, token, client, request):# pylint: disable=[unused-argument, no-self-use]
+        """Check that the client has permission to introspect token."""
+        return client.client_type == "internal"
diff --git a/gn_auth/auth/authentication/oauth2/endpoints/revocation.py b/gn_auth/auth/authentication/oauth2/endpoints/revocation.py
new file mode 100644
index 0000000..b8517b6
--- /dev/null
+++ b/gn_auth/auth/authentication/oauth2/endpoints/revocation.py
@@ -0,0 +1,22 @@
+"""Handle token revocation."""
+
+from flask import current_app
+from authlib.oauth2.rfc7009 import RevocationEndpoint as _RevocationEndpoint
+
+from gn3.auth import db
+from gn3.auth.authentication.oauth2.models.oauth2token import (
+    save_token, OAuth2Token, revoke_token)
+
+from .utilities import query_token as _query_token
+
+class RevocationEndpoint(_RevocationEndpoint):
+    """Revoke the tokens"""
+    ENDPOINT_NAME = "revoke"
+    def query_token(self, token_string: str, token_type_hint: str):
+        """Query the token."""
+        return _query_token(self, token_string, token_type_hint)
+
+    def revoke_token(self, token: OAuth2Token, request):
+        """Revoke token `token`."""
+        with db.connection(current_app.config["AUTH_DB"]) as conn:
+            save_token(conn, revoke_token(token))
diff --git a/gn_auth/auth/authentication/oauth2/endpoints/utilities.py b/gn_auth/auth/authentication/oauth2/endpoints/utilities.py
new file mode 100644
index 0000000..299f151
--- /dev/null
+++ b/gn_auth/auth/authentication/oauth2/endpoints/utilities.py
@@ -0,0 +1,30 @@
+"""endpoint utilities"""
+from typing import Any, Optional
+
+from flask import current_app
+from pymonad.maybe import Nothing
+
+from gn3.auth import db
+from gn3.auth.authentication.oauth2.models.oauth2token import (
+    OAuth2Token, token_by_access_token, token_by_refresh_token)
+
+def query_token(# pylint: disable=[unused-argument]
+        endpoint_object: Any, token_str: str, token_type_hint) -> Optional[
+            OAuth2Token]:
+    """Retrieve the token from the database."""
+    __identity__ = lambda val: val
+    token = Nothing
+    with db.connection(current_app.config["AUTH_DB"]) as conn:
+        if token_type_hint == "access_token":
+            token = token_by_access_token(conn, token_str)
+        if token_type_hint == "access_token":
+            token = token_by_refresh_token(conn, token_str)
+
+        return token.maybe(
+            token_by_access_token(conn, token_str).maybe(
+                token_by_refresh_token(conn, token_str).maybe(
+                    None, __identity__),
+                __identity__),
+            __identity__)
+
+    return None
diff --git a/gn_auth/auth/authentication/oauth2/grants/__init__.py b/gn_auth/auth/authentication/oauth2/grants/__init__.py
new file mode 100644
index 0000000..e69de29
--- /dev/null
+++ b/gn_auth/auth/authentication/oauth2/grants/__init__.py
diff --git a/gn_auth/auth/authentication/oauth2/grants/authorisation_code_grant.py b/gn_auth/auth/authentication/oauth2/grants/authorisation_code_grant.py
new file mode 100644
index 0000000..f80d02e
--- /dev/null
+++ b/gn_auth/auth/authentication/oauth2/grants/authorisation_code_grant.py
@@ -0,0 +1,85 @@
+"""Classes and function for Authorisation Code flow."""
+import uuid
+import string
+import random
+from typing import Optional
+from datetime import datetime
+
+from flask import current_app as app
+from authlib.oauth2.rfc6749 import grants
+from authlib.oauth2.rfc7636 import create_s256_code_challenge
+
+from gn3.auth import db
+from gn3.auth.db_utils import with_db_connection
+from gn3.auth.authentication.users import User
+
+from ..models.oauth2client import OAuth2Client
+from ..models.authorization_code import (
+    AuthorisationCode, authorisation_code, save_authorisation_code)
+
+class AuthorisationCodeGrant(grants.AuthorizationCodeGrant):
+    """Implement the 'Authorisation Code' grant."""
+    TOKEN_ENDPOINT_AUTH_METHODS: list[str] = [
+        "client_secret_basic", "client_secret_post"]
+    AUTHORIZATION_CODE_LENGTH: int = 48
+    TOKEN_ENDPOINT_HTTP_METHODS = ['POST']
+    GRANT_TYPE = "authorization_code"
+    RESPONSE_TYPES = {'code'}
+
+    def save_authorization_code(self, code, request):
+        """Persist the authorisation code to database."""
+        client = request.client
+        nonce = "".join(random.sample(string.ascii_letters + string.digits,
+                                      k=self.AUTHORIZATION_CODE_LENGTH))
+        return __save_authorization_code__(AuthorisationCode(
+            uuid.uuid4(), code, client, request.redirect_uri, request.scope,
+            nonce, int(datetime.now().timestamp()),
+            create_s256_code_challenge(app.config["SECRET_KEY"]),
+            "S256", request.user))
+
+    def query_authorization_code(self, code, client):
+        """Retrieve the code from the database."""
+        return __query_authorization_code__(code, client)
+
+    def delete_authorization_code(self, authorization_code):# pylint: disable=[no-self-use]
+        """Delete the authorisation code."""
+        with db.connection(app.config["AUTH_DB"]) as conn:
+            with db.cursor(conn) as cursor:
+                cursor.execute(
+                    "DELETE FROM authorisation_code WHERE code_id=?",
+                    (str(authorization_code.code_id),))
+
+    def authenticate_user(self, authorization_code) -> Optional[User]:
+        """Authenticate the user who own the authorisation code."""
+        query = (
+            "SELECT users.* FROM authorisation_code LEFT JOIN users "
+            "ON authorisation_code.user_id=users.user_id "
+            "WHERE authorisation_code.code=?")
+        with db.connection(app.config["AUTH_DB"]) as conn:
+            with db.cursor(conn) as cursor:
+                cursor.execute(query, (str(authorization_code.code),))
+                res = cursor.fetchone()
+                if res:
+                    return User(
+                        uuid.UUID(res["user_id"]), res["email"], res["name"])
+
+        return None
+
+def __query_authorization_code__(
+        code: str, client: OAuth2Client) -> AuthorisationCode:
+    """A helper function that creates a new database connection.
+
+    This is found to be necessary since the `AuthorizationCodeGrant` class(es)
+    do not have a way to pass the database connection."""
+    def __auth_code__(conn) -> str:
+        the_code = authorisation_code(conn, code, client)
+        return the_code.maybe(None, lambda cde: cde) # type: ignore[misc, arg-type, return-value]
+
+    return with_db_connection(__auth_code__)
+
+def __save_authorization_code__(code: AuthorisationCode) -> AuthorisationCode:
+    """A helper function that creates a new database connection.
+
+    This is found to be necessary since the `AuthorizationCodeGrant` class(es)
+    do not have a way to pass the database connection."""
+    return with_db_connection(lambda conn: save_authorisation_code(conn, code))
diff --git a/gn_auth/auth/authentication/oauth2/grants/password_grant.py b/gn_auth/auth/authentication/oauth2/grants/password_grant.py
new file mode 100644
index 0000000..3233877
--- /dev/null
+++ b/gn_auth/auth/authentication/oauth2/grants/password_grant.py
@@ -0,0 +1,22 @@
+"""Allows users to authenticate directly."""
+
+from flask import current_app as app
+from authlib.oauth2.rfc6749 import grants
+
+from gn3.auth import db
+from gn3.auth.authentication.users import valid_login, user_by_email
+
+from gn3.auth.authorisation.errors import NotFoundError
+
+class PasswordGrant(grants.ResourceOwnerPasswordCredentialsGrant):
+    """Implement the 'Password' grant."""
+    TOKEN_ENDPOINT_AUTH_METHODS = ["client_secret_basic", "client_secret_post"]
+
+    def authenticate_user(self, username, password):
+        "Authenticate the user with their username and password."
+        with db.connection(app.config["AUTH_DB"]) as conn:
+            try:
+                user = user_by_email(conn, username)
+                return user if valid_login(conn, user, password) else None
+            except NotFoundError as _nfe:
+                return None
diff --git a/gn_auth/auth/authentication/oauth2/models/__init__.py b/gn_auth/auth/authentication/oauth2/models/__init__.py
new file mode 100644
index 0000000..e69de29
--- /dev/null
+++ b/gn_auth/auth/authentication/oauth2/models/__init__.py
diff --git a/gn_auth/auth/authentication/oauth2/models/authorization_code.py b/gn_auth/auth/authentication/oauth2/models/authorization_code.py
new file mode 100644
index 0000000..f282814
--- /dev/null
+++ b/gn_auth/auth/authentication/oauth2/models/authorization_code.py
@@ -0,0 +1,93 @@
+"""Model and functions for handling the Authorisation Code"""
+from uuid import UUID
+from datetime import datetime
+from typing import NamedTuple
+
+from pymonad.maybe import Just, Maybe, Nothing
+
+from gn3.auth import db
+
+from .oauth2client import OAuth2Client
+
+from ...users import User, user_by_id
+
+__5_MINUTES__ = 300 # in seconds
+
+class AuthorisationCode(NamedTuple):
+    """
+    The AuthorisationCode model for the auth(entic|oris)ation system.
+    """
+    # Instance variables
+    code_id: UUID
+    code: str
+    client: OAuth2Client
+    redirect_uri: str
+    scope: str
+    nonce: str
+    auth_time: int
+    code_challenge: str
+    code_challenge_method: str
+    user: User
+
+    @property
+    def response_type(self) -> str:
+        """
+        For authorisation code flow, the response_type type MUST always be
+        'code'.
+        """
+        return "code"
+
+    def is_expired(self):
+        """Check whether the code is expired."""
+        return self.auth_time + __5_MINUTES__ < datetime.now().timestamp()
+
+    def get_redirect_uri(self):
+        """Get the redirect URI"""
+        return self.redirect_uri
+
+    def get_scope(self):
+        """Return the assigned scope for this AuthorisationCode."""
+        return self.scope
+
+    def get_nonce(self):
+        """Get the one-time use token."""
+        return self.nonce
+
+def authorisation_code(conn: db.DbConnection ,
+                       code: str,
+                       client: OAuth2Client) -> Maybe[AuthorisationCode]:
+    """
+    Retrieve the authorisation code object that corresponds to `code` and the
+    given OAuth2 client.
+    """
+    with db.cursor(conn) as cursor:
+        query = ("SELECT * FROM authorisation_code "
+                 "WHERE code=:code AND client_id=:client_id")
+        cursor.execute(
+            query, {"code": code, "client_id": str(client.client_id)})
+        result = cursor.fetchone()
+        if result:
+            return Just(AuthorisationCode(
+                UUID(result["code_id"]), result["code"], client,
+                result["redirect_uri"], result["scope"], result["nonce"],
+                int(result["auth_time"]), result["code_challenge"],
+                result["code_challenge_method"],
+                user_by_id(conn, UUID(result["user_id"]))))
+        return Nothing
+
+def save_authorisation_code(conn: db.DbConnection,
+                            auth_code: AuthorisationCode) -> AuthorisationCode:
+    """Persist the `auth_code` into the database."""
+    with db.cursor(conn) as cursor:
+        cursor.execute(
+            "INSERT INTO authorisation_code VALUES("
+            ":code_id, :code, :client_id, :redirect_uri, :scope, :nonce, "
+            ":auth_time, :code_challenge, :code_challenge_method, :user_id"
+            ")",
+            {
+                **auth_code._asdict(),
+                "code_id": str(auth_code.code_id),
+                "client_id": str(auth_code.client.client_id),
+                "user_id": str(auth_code.user.user_id)
+            })
+        return auth_code
diff --git a/gn_auth/auth/authentication/oauth2/models/oauth2client.py b/gn_auth/auth/authentication/oauth2/models/oauth2client.py
new file mode 100644
index 0000000..2a307e3
--- /dev/null
+++ b/gn_auth/auth/authentication/oauth2/models/oauth2client.py
@@ -0,0 +1,234 @@
+"""OAuth2 Client model."""
+import json
+import datetime
+from uuid import UUID
+from typing import Sequence, Optional, NamedTuple
+
+from pymonad.maybe import Just, Maybe, Nothing
+
+from gn3.auth import db
+from gn3.auth.authentication.users import User, users, user_by_id, same_password
+
+from gn3.auth.authorisation.errors import NotFoundError
+
+class OAuth2Client(NamedTuple):
+    """
+    Client to the OAuth2 Server.
+
+    This is defined according to the mixin at
+    https://docs.authlib.org/en/latest/specs/rfc6749.html#authlib.oauth2.rfc6749.ClientMixin
+    """
+    client_id: UUID
+    client_secret: str
+    client_id_issued_at: datetime.datetime
+    client_secret_expires_at: datetime.datetime
+    client_metadata: dict
+    user: User
+
+    def check_client_secret(self, client_secret: str) -> bool:
+        """Check whether the `client_secret` matches this client."""
+        return same_password(client_secret, self.client_secret)
+
+    @property
+    def token_endpoint_auth_method(self) -> str:
+        """Return the token endpoint authorisation method."""
+        return self.client_metadata.get("token_endpoint_auth_method", ["none"])
+
+    @property
+    def client_type(self) -> str:
+        """
+        Return the token endpoint authorisation method.
+
+        Acceptable client types:
+        * public: Unable to use registered client secrets, e.g. browsers, apps
+          on mobile devices.
+        * confidential: able to securely authenticate with authorisation server
+          e.g. being able to keep their registered client secret safe.
+        """
+        return self.client_metadata.get("client_type", "public")
+
+    def check_endpoint_auth_method(self, method: str, endpoint: str) -> bool:
+        """
+        Check if the client supports the given method for the given endpoint.
+
+        Acceptable methods:
+        * none: Client is a public client and does not have a client secret
+        * client_secret_post: Client uses the HTTP POST parameters
+        * client_secret_basic: Client uses HTTP Basic
+        """
+        if endpoint == "token":
+            return (method in self.token_endpoint_auth_method
+                    and method == "client_secret_post")
+        if endpoint in ("introspection", "revoke"):
+            return (method in self.token_endpoint_auth_method
+                    and method == "client_secret_basic")
+        return False
+
+    @property
+    def id(self):# pylint: disable=[invalid-name]
+        """Return the client_id."""
+        return self.client_id
+
+    @property
+    def grant_types(self) -> Sequence[str]:
+        """
+        Return the grant types that this client supports.
+
+        Valid grant types:
+        * authorisation_code
+        * implicit
+        * client_credentials
+        * password
+        """
+        return self.client_metadata.get("grant_types", [])
+
+    def check_grant_type(self, grant_type: str) -> bool:
+        """
+        Validate that client can handle the given grant types
+        """
+        return grant_type in self.grant_types
+
+    @property
+    def redirect_uris(self) -> Sequence[str]:
+        """Return the redirect_uris that this client supports."""
+        return self.client_metadata.get('redirect_uris', [])
+
+    def check_redirect_uri(self, redirect_uri: str) -> bool:
+        """
+        Check whether the given `redirect_uri` is one of the expected ones.
+        """
+        return redirect_uri in self.redirect_uris
+
+    @property
+    def response_types(self) -> Sequence[str]:
+        """Return the response_types that this client supports."""
+        return self.client_metadata.get("response_type", [])
+
+    def check_response_type(self, response_type: str) -> bool:
+        """Check whether this client supports `response_type`."""
+        return response_type in self.response_types
+
+    @property
+    def scope(self) -> Sequence[str]:
+        """Return valid scopes for this client."""
+        return tuple(set(self.client_metadata.get("scope", [])))
+
+    def get_allowed_scope(self, scope: str) -> str:
+        """Return list of scopes in `scope` that are supported by this client."""
+        if not bool(scope):
+            return ""
+        requested = scope.split()
+        return " ".join(sorted(set(
+            scp for scp in requested if scp in self.scope)))
+
+    def get_client_id(self):
+        """Return this client's identifier."""
+        return self.client_id
+
+    def get_default_redirect_uri(self) -> str:
+        """Return the default redirect uri"""
+        return self.client_metadata.get("default_redirect_uri", "")
+
+def client(conn: db.DbConnection, client_id: UUID,
+           user: Optional[User] = None) -> Maybe:
+    """Retrieve a client by its ID"""
+    with db.cursor(conn) as cursor:
+        cursor.execute(
+            "SELECT * FROM oauth2_clients WHERE client_id=?", (str(client_id),))
+        result = cursor.fetchone()
+        the_user = user
+        if result:
+            if not bool(the_user):
+                try:
+                    the_user = user_by_id(conn, result["user_id"])
+                except NotFoundError as _nfe:
+                    the_user = None
+
+            return Just(
+                OAuth2Client(UUID(result["client_id"]),
+                             result["client_secret"],
+                             datetime.datetime.fromtimestamp(
+                                 result["client_id_issued_at"]),
+                             datetime.datetime.fromtimestamp(
+                                 result["client_secret_expires_at"]),
+                             json.loads(result["client_metadata"]),
+                             the_user))# type: ignore[arg-type]
+
+    return Nothing
+
+def client_by_id_and_secret(conn: db.DbConnection, client_id: UUID,
+                            client_secret: str) -> OAuth2Client:
+    """Retrieve a client by its ID and secret"""
+    with db.cursor(conn) as cursor:
+        cursor.execute(
+            "SELECT * FROM oauth2_clients WHERE client_id=?",
+            (str(client_id),))
+        row = cursor.fetchone()
+        if bool(row) and same_password(client_secret, row["client_secret"]):
+            return OAuth2Client(
+                client_id, client_secret,
+                datetime.datetime.fromtimestamp(row["client_id_issued_at"]),
+                datetime.datetime.fromtimestamp(
+                    row["client_secret_expires_at"]),
+                json.loads(row["client_metadata"]),
+                user_by_id(conn, UUID(row["user_id"])))
+
+        raise NotFoundError("Could not find client with the given credentials.")
+
+def save_client(conn: db.DbConnection, the_client: OAuth2Client) -> OAuth2Client:
+    """Persist the client details into the database."""
+    with db.cursor(conn) as cursor:
+        query = (
+            "INSERT INTO oauth2_clients "
+            "(client_id, client_secret, client_id_issued_at, "
+            "client_secret_expires_at, client_metadata, user_id) "
+            "VALUES "
+            "(:client_id, :client_secret, :client_id_issued_at, "
+            ":client_secret_expires_at, :client_metadata, :user_id) "
+            "ON CONFLICT (client_id) DO UPDATE SET "
+            "client_secret=:client_secret, "
+            "client_id_issued_at=:client_id_issued_at, "
+            "client_secret_expires_at=:client_secret_expires_at, "
+            "client_metadata=:client_metadata, user_id=:user_id")
+        cursor.execute(
+            query,
+            {
+                "client_id": str(the_client.client_id),
+                "client_secret": the_client.client_secret,
+                "client_id_issued_at": (
+                    the_client.client_id_issued_at.timestamp()),
+                "client_secret_expires_at": (
+                    the_client.client_secret_expires_at.timestamp()),
+                "client_metadata": json.dumps(the_client.client_metadata),
+                "user_id": str(the_client.user.user_id)
+            })
+        return the_client
+
+def oauth2_clients(conn: db.DbConnection) -> tuple[OAuth2Client, ...]:
+    """Fetch a list of all OAuth2 clients."""
+    with db.cursor(conn) as cursor:
+        cursor.execute("SELECT * FROM oauth2_clients")
+        clients_rs = cursor.fetchall()
+        the_users = {
+            usr.user_id: usr for usr in users(
+                conn, tuple({UUID(result["user_id"]) for result in clients_rs}))
+        }
+        return tuple(OAuth2Client(UUID(result["client_id"]),
+                                  result["client_secret"],
+                                  datetime.datetime.fromtimestamp(
+                                     result["client_id_issued_at"]),
+                                  datetime.datetime.fromtimestamp(
+                                     result["client_secret_expires_at"]),
+                                  json.loads(result["client_metadata"]),
+                                  the_users[UUID(result["user_id"])])
+                     for result in clients_rs)
+
+def delete_client(conn: db.DbConnection, the_client: OAuth2Client) -> OAuth2Client:
+    """Delete the given client from the database"""
+    with db.cursor(conn) as cursor:
+        params = (str(the_client.client_id),)
+        cursor.execute("DELETE FROM authorisation_code WHERE client_id=?",
+                       params)
+        cursor.execute("DELETE FROM oauth2_tokens WHERE client_id=?", params)
+        cursor.execute("DELETE FROM oauth2_clients WHERE client_id=?", params)
+        return the_client
diff --git a/gn_auth/auth/authentication/oauth2/models/oauth2token.py b/gn_auth/auth/authentication/oauth2/models/oauth2token.py
new file mode 100644
index 0000000..72e20cc
--- /dev/null
+++ b/gn_auth/auth/authentication/oauth2/models/oauth2token.py
@@ -0,0 +1,132 @@
+"""OAuth2 Token"""
+import uuid
+import datetime
+from typing import NamedTuple, Optional
+
+from pymonad.maybe import Just, Maybe, Nothing
+
+from gn3.auth import db
+from gn3.auth.authentication.users import User, user_by_id
+
+from gn3.auth.authorisation.errors import NotFoundError
+
+from .oauth2client import client, OAuth2Client
+
+class OAuth2Token(NamedTuple):
+    """Implement Tokens for OAuth2."""
+    token_id: uuid.UUID
+    client: OAuth2Client
+    token_type: str
+    access_token: str
+    refresh_token: Optional[str]
+    scope: str
+    revoked: bool
+    issued_at: datetime.datetime
+    expires_in: int
+    user: User
+
+    @property
+    def expires_at(self) -> datetime.datetime:
+        """Return the time when the token expires."""
+        return self.issued_at + datetime.timedelta(seconds=self.expires_in)
+
+    def check_client(self, client: OAuth2Client) -> bool:# pylint: disable=[redefined-outer-name]
+        """Check whether the token is issued to given `client`."""
+        return client.client_id == self.client.client_id
+
+    def get_expires_in(self) -> int:
+        """Return the `expires_in` value for the token."""
+        return self.expires_in
+
+    def get_scope(self) -> str:
+        """Return the valid scope for the token."""
+        return self.scope
+
+    def is_expired(self) -> bool:
+        """Check whether the token is expired."""
+        return self.expires_at < datetime.datetime.now()
+
+    def is_revoked(self):
+        """Check whether the token has been revoked."""
+        return self.revoked
+
+def __token_from_resultset__(conn: db.DbConnection, rset) -> Maybe:
+    __identity__ = lambda val: val
+    try:
+        the_user = user_by_id(conn, uuid.UUID(rset["user_id"]))
+    except NotFoundError as _nfe:
+        the_user = None
+    the_client = client(conn, uuid.UUID(rset["client_id"]), the_user)
+
+    if the_client.is_just() and bool(the_user):
+        return Just(OAuth2Token(token_id=uuid.UUID(rset["token_id"]),
+                                client=the_client.maybe(None, __identity__),
+                                token_type=rset["token_type"],
+                                access_token=rset["access_token"],
+                                refresh_token=rset["refresh_token"],
+                                scope=rset["scope"],
+                                revoked=(rset["revoked"] == 1),
+                                issued_at=datetime.datetime.fromtimestamp(
+                                    rset["issued_at"]),
+                                expires_in=rset["expires_in"],
+                                user=the_user))# type: ignore[arg-type]
+
+    return Nothing
+
+def token_by_access_token(conn: db.DbConnection, token_str: str) -> Maybe:
+    """Retrieve token by its token string"""
+    with db.cursor(conn) as cursor:
+        cursor.execute("SELECT * FROM oauth2_tokens WHERE access_token=?",
+                       (token_str,))
+        res = cursor.fetchone()
+        if res:
+            return __token_from_resultset__(conn, res)
+
+    return Nothing
+
+def token_by_refresh_token(conn: db.DbConnection, token_str: str) -> Maybe:
+    """Retrieve token by its token string"""
+    with db.cursor(conn) as cursor:
+        cursor.execute(
+            "SELECT * FROM oauth2_tokens WHERE refresh_token=?",
+            (token_str,))
+        res = cursor.fetchone()
+        if res:
+            return __token_from_resultset__(conn, res)
+
+    return Nothing
+
+def revoke_token(token: OAuth2Token) -> OAuth2Token:
+    """
+    Return a new token derived from `token` with the `revoked` field set to
+    `True`.
+    """
+    return OAuth2Token(
+        token_id=token.token_id, client=token.client,
+        token_type=token.token_type, access_token=token.access_token,
+        refresh_token=token.refresh_token, scope=token.scope, revoked=True,
+        issued_at=token.issued_at, expires_in=token.expires_in, user=token.user)
+
+def save_token(conn: db.DbConnection, token: OAuth2Token) -> None:
+    """Save/Update the token."""
+    with db.cursor(conn) as cursor:
+        cursor.execute(
+            ("INSERT INTO oauth2_tokens VALUES (:token_id, :client_id, "
+             ":token_type, :access_token, :refresh_token, :scope, :revoked, "
+             ":issued_at, :expires_in, :user_id) "
+             "ON CONFLICT (token_id) DO UPDATE SET "
+             "refresh_token=:refresh_token, revoked=:revoked, "
+             "expires_in=:expires_in "
+             "WHERE token_id=:token_id"),
+            {
+                "token_id": str(token.token_id),
+                "client_id": str(token.client.client_id),
+                "token_type": token.token_type,
+                "access_token": token.access_token,
+                "refresh_token": token.refresh_token,
+                "scope": token.scope,
+                "revoked": 1 if token.revoked else 0,
+                "issued_at": int(token.issued_at.timestamp()),
+                "expires_in": token.expires_in,
+                "user_id": str(token.user.user_id)
+            })
diff --git a/gn_auth/auth/authentication/oauth2/resource_server.py b/gn_auth/auth/authentication/oauth2/resource_server.py
new file mode 100644
index 0000000..223e811
--- /dev/null
+++ b/gn_auth/auth/authentication/oauth2/resource_server.py
@@ -0,0 +1,19 @@
+"""Protect the resources endpoints"""
+
+from flask import current_app as app
+from authlib.oauth2.rfc6750 import BearerTokenValidator as _BearerTokenValidator
+from authlib.integrations.flask_oauth2 import ResourceProtector
+
+from gn3.auth import db
+from gn3.auth.authentication.oauth2.models.oauth2token import token_by_access_token
+
+class BearerTokenValidator(_BearerTokenValidator):
+    """Extends `authlib.oauth2.rfc6750.BearerTokenValidator`"""
+    def authenticate_token(self, token_string: str):
+        with db.connection(app.config["AUTH_DB"]) as conn:
+            return token_by_access_token(conn, token_string).maybe(# type: ignore[misc]
+                None, lambda tok: tok)
+
+require_oauth = ResourceProtector()
+
+require_oauth.register_token_validator(BearerTokenValidator())
diff --git a/gn_auth/auth/authentication/oauth2/server.py b/gn_auth/auth/authentication/oauth2/server.py
new file mode 100644
index 0000000..7d7113a
--- /dev/null
+++ b/gn_auth/auth/authentication/oauth2/server.py
@@ -0,0 +1,72 @@
+"""Initialise the OAuth2 Server"""
+import uuid
+import datetime
+from typing import Callable
+
+from flask import Flask, current_app
+from authlib.oauth2.rfc6749.errors import InvalidClientError
+from authlib.integrations.flask_oauth2 import AuthorizationServer
+# from authlib.oauth2.rfc7636 import CodeChallenge
+
+from gn3.auth import db
+
+from .models.oauth2client import client
+from .models.oauth2token import OAuth2Token, save_token
+
+from .grants.password_grant import PasswordGrant
+from .grants.authorisation_code_grant import AuthorisationCodeGrant
+
+from .endpoints.revocation import RevocationEndpoint
+from .endpoints.introspection import IntrospectionEndpoint
+
+def create_query_client_func() -> Callable:
+    """Create the function that loads the client."""
+    def __query_client__(client_id: uuid.UUID):
+        # use current_app rather than passing the db_uri to avoid issues
+        # when config changes, e.g. while testing.
+        with db.connection(current_app.config["AUTH_DB"]) as conn:
+            the_client = client(conn, client_id).maybe(
+                None, lambda clt: clt) # type: ignore[misc]
+            if bool(the_client):
+                return the_client
+            raise InvalidClientError(
+                "No client found for the given CLIENT_ID and CLIENT_SECRET.")
+
+    return __query_client__
+
+def create_save_token_func(token_model: type) -> Callable:
+    """Create the function that saves the token."""
+    def __save_token__(token, request):
+        with db.connection(current_app.config["AUTH_DB"]) as conn:
+            save_token(
+                conn, token_model(
+                    token_id=uuid.uuid4(), client=request.client,
+                    user=request.user,
+                    **{
+                        "refresh_token": None, "revoked": False,
+                        "issued_at": datetime.datetime.now(),
+                        **token
+                    }))
+
+    return __save_token__
+
+def setup_oauth2_server(app: Flask) -> None:
+    """Set's up the oauth2 server for the flask application."""
+    server = AuthorizationServer()
+    server.register_grant(PasswordGrant)
+
+    # Figure out a common `code_verifier` for GN2 and GN3 and set
+    # server.register_grant(AuthorisationCodeGrant, [CodeChallenge(required=False)])
+    # below
+    server.register_grant(AuthorisationCodeGrant)
+
+    # register endpoints
+    server.register_endpoint(RevocationEndpoint)
+    server.register_endpoint(IntrospectionEndpoint)
+
+    # init server
+    server.init_app(
+        app,
+        query_client=create_query_client_func(),
+        save_token=create_save_token_func(OAuth2Token))
+    app.config["OAUTH2_SERVER"] = server
diff --git a/gn_auth/auth/authentication/oauth2/views.py b/gn_auth/auth/authentication/oauth2/views.py
new file mode 100644
index 0000000..2bd3865
--- /dev/null
+++ b/gn_auth/auth/authentication/oauth2/views.py
@@ -0,0 +1,104 @@
+"""Endpoints for the oauth2 server"""
+import uuid
+import traceback
+
+from authlib.oauth2.rfc6749.errors import InvalidClientError
+from email_validator import validate_email, EmailNotValidError
+from flask import (
+    flash,
+    request,
+    url_for,
+    redirect,
+    Response,
+    Blueprint,
+    render_template,
+    current_app as app)
+
+from gn3.auth import db
+from gn3.auth.db_utils import with_db_connection
+from gn3.auth.authorisation.errors import ForbiddenAccess
+
+from .resource_server import require_oauth
+from .endpoints.revocation import RevocationEndpoint
+from .endpoints.introspection import IntrospectionEndpoint
+
+from ..users import valid_login, NotFoundError, user_by_email
+
+auth = Blueprint("auth", __name__)
+
+@auth.route("/delete-client/<uuid:client_id>", methods=["GET", "POST"])
+def delete_client(client_id: uuid.UUID):
+    """Delete an OAuth2 client."""
+    return f"WOULD DELETE OAUTH2 CLIENT {client_id}."
+
+@auth.route("/authorise", methods=["GET", "POST"])
+def authorise():
+    """Authorise a user"""
+    try:
+        server = app.config["OAUTH2_SERVER"]
+        client_id = uuid.UUID(request.args.get(
+            "client_id",
+            request.form.get("client_id", str(uuid.uuid4()))))
+        client = server.query_client(client_id)
+        if not bool(client):
+            flash("Invalid OAuth2 client.", "alert-error")
+        if request.method == "GET":
+            client = server.query_client(request.args.get("client_id"))
+            return render_template(
+                "oauth2/authorise-user.html",
+                client=client,
+                scope=client.scope,
+                response_type="code")
+
+        form = request.form
+        def __authorise__(conn: db.DbConnection) -> Response:
+            email_passwd_msg = "Email or password is invalid!"
+            redirect_response = redirect(url_for("oauth2.auth.authorise",
+                                                 client_id=client_id))
+            try:
+                email = validate_email(
+                    form.get("user:email"), check_deliverability=False)
+                user = user_by_email(conn, email["email"])
+                if valid_login(conn, user, form.get("user:password", "")):
+                    return server.create_authorization_response(request=request, grant_user=user)
+                flash(email_passwd_msg, "alert-error")
+                return redirect_response # type: ignore[return-value]
+            except EmailNotValidError as _enve:
+                app.logger.debug(traceback.format_exc())
+                flash(email_passwd_msg, "alert-error")
+                return redirect_response # type: ignore[return-value]
+            except NotFoundError as _nfe:
+                app.logger.debug(traceback.format_exc())
+                flash(email_passwd_msg, "alert-error")
+                return redirect_response # type: ignore[return-value]
+
+        return with_db_connection(__authorise__)
+    except InvalidClientError as ice:
+        return render_template(
+            "oauth2/oauth2_error.html", error=ice), ice.status_code
+
+@auth.route("/token", methods=["POST"])
+def token():
+    """Retrieve the authorisation token."""
+    server = app.config["OAUTH2_SERVER"]
+    return server.create_token_response()
+
+@auth.route("/revoke", methods=["POST"])
+def revoke_token():
+    """Revoke the token."""
+    return app.config["OAUTH2_SERVER"].create_endpoint_response(
+        RevocationEndpoint.ENDPOINT_NAME)
+
+@auth.route("/introspect", methods=["POST"])
+@require_oauth("introspect")
+def introspect_token() -> Response:
+    """Provide introspection information for the token."""
+    # This is dangerous to provide publicly
+    authorised_clients = app.config.get(
+        "OAUTH2_CLIENTS_WITH_INTROSPECTION_PRIVILEGE", [])
+    with require_oauth.acquire("introspect") as the_token:
+        if the_token.client.client_id in authorised_clients:
+            return app.config["OAUTH2_SERVER"].create_endpoint_response(
+                IntrospectionEndpoint.ENDPOINT_NAME)
+
+    raise ForbiddenAccess("You cannot access this endpoint")
diff --git a/gn_auth/auth/authentication/users.py b/gn_auth/auth/authentication/users.py
new file mode 100644
index 0000000..0e72ed2
--- /dev/null
+++ b/gn_auth/auth/authentication/users.py
@@ -0,0 +1,128 @@
+"""User-specific code and data structures."""
+from uuid import UUID, uuid4
+from typing import Any, Tuple, NamedTuple
+
+from argon2 import PasswordHasher
+from argon2.exceptions import VerifyMismatchError
+
+from gn3.auth import db
+from gn3.auth.authorisation.errors import NotFoundError
+
+class User(NamedTuple):
+    """Class representing a user."""
+    user_id: UUID
+    email: str
+    name: str
+
+    def get_user_id(self):
+        """Return the user's UUID. Mostly for use with Authlib."""
+        return self.user_id
+
+    def dictify(self) -> dict[str, Any]:
+        """Return a dict representation of `User` objects."""
+        return {"user_id": self.user_id, "email": self.email, "name": self.name}
+
+DUMMY_USER = User(user_id=UUID("a391cf60-e8b7-4294-bd22-ddbbda4b3530"),
+                  email="gn3@dummy.user",
+                  name="Dummy user to use as placeholder")
+
+def user_by_email(conn: db.DbConnection, email: str) -> User:
+    """Retrieve user from database by their email address"""
+    with db.cursor(conn) as cursor:
+        cursor.execute("SELECT * FROM users WHERE email=?", (email,))
+        row = cursor.fetchone()
+
+    if row:
+        return User(UUID(row["user_id"]), row["email"], row["name"])
+
+    raise NotFoundError(f"Could not find user with email {email}")
+
+def user_by_id(conn: db.DbConnection, user_id: UUID) -> User:
+    """Retrieve user from database by their user id"""
+    with db.cursor(conn) as cursor:
+        cursor.execute("SELECT * FROM users WHERE user_id=?", (str(user_id),))
+        row = cursor.fetchone()
+
+    if row:
+        return User(UUID(row["user_id"]), row["email"], row["name"])
+
+    raise NotFoundError(f"Could not find user with ID {user_id}")
+
+def same_password(password: str, hashed: str) -> bool:
+    """Check that `raw_password` is hashed to `hash`"""
+    try:
+        return hasher().verify(hashed, password)
+    except VerifyMismatchError as _vme:
+        return False
+
+def valid_login(conn: db.DbConnection, user: User, password: str) -> bool:
+    """Check the validity of the provided credentials for login."""
+    with db.cursor(conn) as cursor:
+        cursor.execute(
+            ("SELECT * FROM users LEFT JOIN user_credentials "
+             "ON users.user_id=user_credentials.user_id "
+             "WHERE users.user_id=?"),
+            (str(user.user_id),))
+        row = cursor.fetchone()
+
+    if row is None:
+        return False
+
+    return same_password(password, row["password"])
+
+def save_user(cursor: db.DbCursor, email: str, name: str) -> User:
+    """
+    Create and persist a user.
+
+    The user creation could be done during a transaction, therefore the function
+    takes a cursor object rather than a connection.
+
+    The newly created and persisted user is then returned.
+    """
+    user_id = uuid4()
+    cursor.execute("INSERT INTO users VALUES (?, ?, ?)",
+                   (str(user_id), email, name))
+    return User(user_id, email, name)
+
+def hasher():
+    """Retrieve PasswordHasher object"""
+    # TODO: Maybe tune the parameters here...
+    # Tuneable Parameters:
+    # - time_cost (default: 2)
+    # - memory_cost (default: 102400)
+    # - parallelism (default: 8)
+    # - hash_len (default: 16)
+    # - salt_len (default: 16)
+    # - encoding (default: 'utf-8')
+    # - type (default: <Type.ID: 2>)
+    return PasswordHasher()
+
+def hash_password(password):
+    """Hash the password."""
+    return hasher().hash(password)
+
+def set_user_password(
+        cursor: db.DbCursor, user: User, password: str) -> Tuple[User, bytes]:
+    """Set the given user's password in the database."""
+    hashed_password = hash_password(password)
+    cursor.execute(
+        ("INSERT INTO user_credentials VALUES (:user_id, :hash) "
+         "ON CONFLICT (user_id) DO UPDATE SET password=:hash"),
+        {"user_id": str(user.user_id), "hash": hashed_password})
+    return user, hashed_password
+
+def users(conn: db.DbConnection,
+          ids: tuple[UUID, ...] = tuple()) -> tuple[User, ...]:
+    """
+    Fetch all users with the given `ids`. If `ids` is empty, return ALL users.
+    """
+    params = ", ".join(["?"] * len(ids))
+    with db.cursor(conn) as cursor:
+        query = "SELECT * FROM users" + (
+            f" WHERE user_id IN ({params})"
+            if len(ids) > 0 else "")
+        print(query)
+        cursor.execute(query, tuple(str(the_id) for the_id in ids))
+        return tuple(User(UUID(row["user_id"]), row["email"], row["name"])
+                     for row in cursor.fetchall())
+    return tuple()
diff --git a/gn_auth/auth/authorisation/__init__.py b/gn_auth/auth/authorisation/__init__.py
new file mode 100644
index 0000000..abd2747
--- /dev/null
+++ b/gn_auth/auth/authorisation/__init__.py
@@ -0,0 +1,2 @@
+"""The authorisation module."""
+from .checks import authorised_p
diff --git a/gn_auth/auth/authorisation/checks.py b/gn_auth/auth/authorisation/checks.py
new file mode 100644
index 0000000..1c87c02
--- /dev/null
+++ b/gn_auth/auth/authorisation/checks.py
@@ -0,0 +1,70 @@
+"""Functions to check for authorisation."""
+from functools import wraps
+from typing import Callable
+
+from flask import request, current_app as app
+
+from gn3.auth import db
+
+from . import privileges as auth_privs
+from .errors import InvalidData, AuthorisationError
+
+from ..authentication.oauth2.resource_server import require_oauth
+
+def __system_privileges_in_roles__(conn, user):
+    """
+    This really is a hack since groups are not treated as resources at the
+    moment of writing this.
+
+    We need a way of allowing the user to have the system:group:* privileges.
+    """
+    query = (
+        "SELECT DISTINCT p.* FROM users AS u "
+        "INNER JOIN group_user_roles_on_resources AS guror "
+        "ON u.user_id=guror.user_id "
+        "INNER JOIN roles AS r ON guror.role_id=r.role_id "
+        "INNER JOIN role_privileges AS rp ON r.role_id=rp.role_id "
+        "INNER JOIN privileges AS p ON rp.privilege_id=p.privilege_id "
+        "WHERE u.user_id=? AND p.privilege_id LIKE 'system:%'")
+    with db.cursor(conn) as cursor:
+        cursor.execute(query, (str(user.user_id),))
+        return (row["privilege_id"] for row in cursor.fetchall())
+
+def authorised_p(
+        privileges: tuple[str, ...],
+        error_description: str = (
+            "You lack authorisation to perform requested action"),
+        oauth2_scope = "profile"):
+    """Authorisation decorator."""
+    assert len(privileges) > 0, "You must provide at least one privilege"
+    def __build_authoriser__(func: Callable):
+        @wraps(func)
+        def __authoriser__(*args, **kwargs):
+            # the_user = user or (hasattr(g, "user") and g.user)
+            with require_oauth.acquire(oauth2_scope) as the_token:
+                the_user = the_token.user
+                if the_user:
+                    with db.connection(app.config["AUTH_DB"]) as conn:
+                        user_privileges = tuple(
+                            priv.privilege_id for priv in
+                            auth_privs.user_privileges(conn, the_user)) + tuple(
+                                priv_id for priv_id in
+                                __system_privileges_in_roles__(conn, the_user))
+
+                    not_assigned = [
+                        priv for priv in privileges if priv not in user_privileges]
+                    if len(not_assigned) == 0:
+                        return func(*args, **kwargs)
+
+                raise AuthorisationError(error_description)
+        return __authoriser__
+    return __build_authoriser__
+
+def require_json(func):
+    """Ensure the request has JSON data."""
+    @wraps(func)
+    def __req_json__(*args, **kwargs):
+        if bool(request.json):
+            return func(*args, **kwargs)
+        raise InvalidData("Expected JSON data in the request.")
+    return __req_json__
diff --git a/gn_auth/auth/authorisation/data/__init__.py b/gn_auth/auth/authorisation/data/__init__.py
new file mode 100644
index 0000000..e69de29
--- /dev/null
+++ b/gn_auth/auth/authorisation/data/__init__.py
diff --git a/gn_auth/auth/authorisation/data/genotypes.py b/gn_auth/auth/authorisation/data/genotypes.py
new file mode 100644
index 0000000..8f901a5
--- /dev/null
+++ b/gn_auth/auth/authorisation/data/genotypes.py
@@ -0,0 +1,96 @@
+"""Handle linking of Genotype data to the Auth(entic|oris)ation system."""
+import uuid
+from typing import Iterable
+
+from MySQLdb.cursors import DictCursor
+
+import gn3.auth.db as authdb
+import gn3.db_utils as gn3db
+from gn3.auth.dictify import dictify
+from gn3.auth.authorisation.checks import authorised_p
+from gn3.auth.authorisation.groups.models import Group
+
+def linked_genotype_data(conn: authdb.DbConnection) -> Iterable[dict]:
+    """Retrive genotype data that is linked to user groups."""
+    with authdb.cursor(conn) as cursor:
+        cursor.execute("SELECT * FROM linked_genotype_data")
+        return (dict(row) for row in cursor.fetchall())
+
+@authorised_p(("system:data:link-to-group",),
+              error_description=(
+                  "You do not have sufficient privileges to link data to (a) "
+                  "group(s)."),
+              oauth2_scope="profile group resource")
+def ungrouped_genotype_data(# pylint: disable=[too-many-arguments]
+        authconn: authdb.DbConnection, gn3conn: gn3db.Connection,
+        search_query: str, selected: tuple[dict, ...] = tuple(),
+        limit: int = 10000, offset: int = 0) -> tuple[
+            dict, ...]:
+    """Retrieve genotype data that is not linked to any user group."""
+    params = tuple(
+        (row["SpeciesId"], row["InbredSetId"], row["GenoFreezeId"])
+            for row in linked_genotype_data(authconn)) + tuple(
+                    (row["SpeciesId"], row["InbredSetId"], row["GenoFreezeId"])
+                    for row in selected)
+    query = (
+        "SELECT s.SpeciesId, iset.InbredSetId, iset.InbredSetName, "
+        "gf.Id AS GenoFreezeId, gf.Name AS dataset_name, "
+        "gf.FullName AS dataset_fullname, "
+        "gf.ShortName AS dataset_shortname "
+        "FROM Species AS s INNER JOIN InbredSet AS iset "
+        "ON s.SpeciesId=iset.SpeciesId INNER JOIN GenoFreeze AS gf "
+        "ON iset.InbredSetId=gf.InbredSetId ")
+
+    if len(params) > 0 or bool(search_query):
+        query = query + "WHERE "
+
+    if len(params) > 0:
+        paramstr = ", ".join(["(%s, %s, %s)"] * len(params))
+        query = query + (
+            "(s.SpeciesId, iset.InbredSetId, gf.Id) "
+            f"NOT IN ({paramstr}) "
+            ) + ("AND " if bool(search_query) else "")
+
+    if bool(search_query):
+        query = query + (
+            "CONCAT(gf.Name, ' ', gf.FullName, ' ', gf.ShortName) LIKE %s ")
+        params = params + ((f"%{search_query}%",),)# type: ignore[operator]
+
+    query = query + f"LIMIT {int(limit)} OFFSET {int(offset)}"
+    with gn3conn.cursor(DictCursor) as cursor:
+        cursor.execute(
+            query, tuple(item for sublist in params for item in sublist))
+        return tuple(row for row in cursor.fetchall())
+
+@authorised_p(
+    ("system:data:link-to-group",),
+    error_description=(
+        "You do not have sufficient privileges to link data to (a) "
+        "group(s)."),
+    oauth2_scope="profile group resource")
+def link_genotype_data(
+        conn: authdb.DbConnection, group: Group, datasets: dict) -> dict:
+    """Link genotye `datasets` to `group`."""
+    with authdb.cursor(conn) as cursor:
+        cursor.executemany(
+            "INSERT INTO linked_genotype_data VALUES "
+            "(:data_link_id, :group_id, :SpeciesId, :InbredSetId, "
+            ":GenoFreezeId, :dataset_name, :dataset_fullname, "
+            ":dataset_shortname) "
+            "ON CONFLICT (SpeciesId, InbredSetId, GenoFreezeId) DO NOTHING",
+            tuple({
+                "data_link_id": str(uuid.uuid4()),
+                "group_id": str(group.group_id),
+                **{
+                    key: value for key,value in dataset.items() if key in (
+                        "GenoFreezeId", "InbredSetId", "SpeciesId",
+                        "dataset_fullname", "dataset_name", "dataset_shortname")
+                }
+            } for dataset in datasets))
+        return {
+            "description": (
+                f"Successfully linked {len(datasets)} to group "
+                f"'{group.group_name}'."),
+            "group": dictify(group),
+            "datasets": datasets
+        }
diff --git a/gn_auth/auth/authorisation/data/mrna.py b/gn_auth/auth/authorisation/data/mrna.py
new file mode 100644
index 0000000..bdfc5c1
--- /dev/null
+++ b/gn_auth/auth/authorisation/data/mrna.py
@@ -0,0 +1,100 @@
+"""Handle linking of mRNA Assay data to the Auth(entic|oris)ation system."""
+import uuid
+from typing import Iterable
+from MySQLdb.cursors import DictCursor
+
+import gn3.auth.db as authdb
+import gn3.db_utils as gn3db
+from gn3.auth.dictify import dictify
+from gn3.auth.authorisation.checks import authorised_p
+from gn3.auth.authorisation.groups.models import Group
+
+def linked_mrna_data(conn: authdb.DbConnection) -> Iterable[dict]:
+    """Retrieve mRNA Assay data that is linked to user groups."""
+    with authdb.cursor(conn) as cursor:
+        cursor.execute("SELECT * FROM linked_mrna_data")
+        return (dict(row) for row in cursor.fetchall())
+
+@authorised_p(("system:data:link-to-group",),
+              error_description=(
+                  "You do not have sufficient privileges to link data to (a) "
+                  "group(s)."),
+              oauth2_scope="profile group resource")
+def ungrouped_mrna_data(# pylint: disable=[too-many-arguments]
+        authconn: authdb.DbConnection, gn3conn: gn3db.Connection,
+        search_query: str, selected: tuple[dict, ...] = tuple(),
+        limit: int = 10000, offset: int = 0) -> tuple[
+            dict, ...]:
+    """Retrieve mrna data that is not linked to any user group."""
+    params = tuple(
+        (row["SpeciesId"], row["InbredSetId"], row["ProbeFreezeId"],
+         row["ProbeSetFreezeId"])
+        for row in linked_mrna_data(authconn)) + tuple(
+                (row["SpeciesId"], row["InbredSetId"], row["ProbeFreezeId"],
+                 row["ProbeSetFreezeId"])
+                for row in selected)
+    query = (
+        "SELECT s.SpeciesId, iset.InbredSetId, iset.InbredSetName, "
+        "pf.ProbeFreezeId, pf.Name AS StudyName, psf.Id AS ProbeSetFreezeId, "
+        "psf.Name AS dataset_name, psf.FullName AS dataset_fullname, "
+        "psf.ShortName AS dataset_shortname "
+        "FROM Species AS s INNER JOIN InbredSet AS iset "
+        "ON s.SpeciesId=iset.SpeciesId INNER JOIN ProbeFreeze AS pf "
+        "ON iset.InbredSetId=pf.InbredSetId INNER JOIN ProbeSetFreeze AS psf "
+        "ON pf.ProbeFreezeId=psf.ProbeFreezeId ") + (
+            "WHERE " if (len(params) > 0 or bool(search_query)) else "")
+
+    if len(params) > 0:
+        paramstr = ", ".join(["(%s, %s, %s, %s)"] * len(params))
+        query = query + (
+            "(s.SpeciesId, iset.InbredSetId, pf.ProbeFreezeId, psf.Id) "
+            f"NOT IN ({paramstr}) "
+            ) + ("AND " if bool(search_query) else "")
+
+    if bool(search_query):
+        query = query + (
+            "CONCAT(pf.Name, psf.Name, ' ', psf.FullName, ' ', psf.ShortName) "
+            "LIKE %s ")
+        params = params + ((f"%{search_query}%",),)# type: ignore[operator]
+
+    query = query + f"LIMIT {int(limit)} OFFSET {int(offset)}"
+    with gn3conn.cursor(DictCursor) as cursor:
+        cursor.execute(
+            query, tuple(item for sublist in params for item in sublist))
+        return tuple(row for row in cursor.fetchall())
+
+@authorised_p(
+    ("system:data:link-to-group",),
+    error_description=(
+        "You do not have sufficient privileges to link data to (a) "
+        "group(s)."),
+    oauth2_scope="profile group resource")
+def link_mrna_data(
+        conn: authdb.DbConnection, group: Group, datasets: dict) -> dict:
+    """Link genotye `datasets` to `group`."""
+    with authdb.cursor(conn) as cursor:
+        cursor.executemany(
+            "INSERT INTO linked_mrna_data VALUES "
+            "(:data_link_id, :group_id, :SpeciesId, :InbredSetId, "
+            ":ProbeFreezeId, :ProbeSetFreezeId, :dataset_name, "
+            ":dataset_fullname, :dataset_shortname) "
+            "ON CONFLICT "
+            "(SpeciesId, InbredSetId, ProbeFreezeId, ProbeSetFreezeId) "
+            "DO NOTHING",
+            tuple({
+                "data_link_id": str(uuid.uuid4()),
+                "group_id": str(group.group_id),
+                **{
+                    key: value for key,value in dataset.items() if key in (
+                        "SpeciesId", "InbredSetId", "ProbeFreezeId",
+                        "ProbeSetFreezeId", "dataset_fullname", "dataset_name",
+                        "dataset_shortname")
+                }
+            } for dataset in datasets))
+        return {
+            "description": (
+                f"Successfully linked {len(datasets)} to group "
+                f"'{group.group_name}'."),
+            "group": dictify(group),
+            "datasets": datasets
+        }
diff --git a/gn_auth/auth/authorisation/data/phenotypes.py b/gn_auth/auth/authorisation/data/phenotypes.py
new file mode 100644
index 0000000..ff98295
--- /dev/null
+++ b/gn_auth/auth/authorisation/data/phenotypes.py
@@ -0,0 +1,140 @@
+"""Handle linking of Phenotype data to the Auth(entic|oris)ation system."""
+import uuid
+from typing import Any, Iterable
+
+from MySQLdb.cursors import DictCursor
+
+import gn3.auth.db as authdb
+import gn3.db_utils as gn3db
+from gn3.auth.dictify import dictify
+from gn3.auth.authorisation.checks import authorised_p
+from gn3.auth.authorisation.groups.models import Group
+
+def linked_phenotype_data(
+        authconn: authdb.DbConnection, gn3conn: gn3db.Connection,
+        species: str = "") -> Iterable[dict[str, Any]]:
+    """Retrieve phenotype data linked to user groups."""
+    authkeys = ("SpeciesId", "InbredSetId", "PublishFreezeId", "PublishXRefId")
+    with (authdb.cursor(authconn) as authcursor,
+          gn3conn.cursor(DictCursor) as gn3cursor):
+        authcursor.execute("SELECT * FROM linked_phenotype_data")
+        linked = tuple(tuple(row[key] for key in authkeys)
+                       for row in authcursor.fetchall())
+        if len(linked) <= 0:
+            return iter(())
+        paramstr = ", ".join(["(%s, %s, %s, %s)"] * len(linked))
+        query = (
+            "SELECT spc.SpeciesId, spc.Name AS SpeciesName, iset.InbredSetId, "
+            "iset.InbredSetName, pf.Id AS PublishFreezeId, "
+            "pf.Name AS dataset_name, pf.FullName AS dataset_fullname, "
+            "pf.ShortName AS dataset_shortname, pxr.Id AS PublishXRefId "
+            "FROM "
+            "Species AS spc "
+            "INNER JOIN InbredSet AS iset "
+            "ON spc.SpeciesId=iset.SpeciesId "
+            "INNER JOIN PublishFreeze AS pf "
+            "ON iset.InbredSetId=pf.InbredSetId "
+            "INNER JOIN PublishXRef AS pxr "
+            "ON pf.InbredSetId=pxr.InbredSetId") + (
+                " WHERE" if (len(linked) > 0 or bool(species)) else "") + (
+                    (" (spc.SpeciesId, iset.InbredSetId, pf.Id, pxr.Id) "
+                     f"IN ({paramstr})") if len(linked) > 0 else "") + (
+                        " AND"if len(linked) > 0 else "") + (
+                        " spc.SpeciesName=%s" if bool(species) else "")
+        params = tuple(item for sublist in linked for item in sublist) + (
+            (species,) if bool(species) else tuple())
+        gn3cursor.execute(query, params)
+        return (item for item in gn3cursor.fetchall())
+
+@authorised_p(("system:data:link-to-group",),
+              error_description=(
+                  "You do not have sufficient privileges to link data to (a) "
+                  "group(s)."),
+              oauth2_scope="profile group resource")
+def ungrouped_phenotype_data(
+        authconn: authdb.DbConnection, gn3conn: gn3db.Connection):
+    """Retrieve phenotype data that is not linked to any user group."""
+    with gn3conn.cursor() as cursor:
+        params = tuple(
+            (row["SpeciesId"], row["InbredSetId"], row["PublishFreezeId"],
+             row["PublishXRefId"])
+            for row in linked_phenotype_data(authconn, gn3conn))
+        paramstr = ", ".join(["(?, ?, ?, ?)"] * len(params))
+        query = (
+            "SELECT spc.SpeciesId, spc.SpeciesName, iset.InbredSetId, "
+            "iset.InbredSetName, pf.Id AS PublishFreezeId, "
+            "pf.Name AS dataset_name, pf.FullName AS dataset_fullname, "
+            "pf.ShortName AS dataset_shortname, pxr.Id AS PublishXRefId "
+            "FROM "
+            "Species AS spc "
+            "INNER JOIN InbredSet AS iset "
+            "ON spc.SpeciesId=iset.SpeciesId "
+            "INNER JOIN PublishFreeze AS pf "
+            "ON iset.InbredSetId=pf.InbredSetId "
+            "INNER JOIN PublishXRef AS pxr "
+            "ON pf.InbredSetId=pxr.InbredSetId")
+        if len(params) > 0:
+            query = query + (
+                f" WHERE (iset.InbredSetId, pf.Id, pxr.Id) NOT IN ({paramstr})")
+
+        cursor.execute(query, params)
+        return tuple(dict(row) for row in cursor.fetchall())
+
+    return tuple()
+
+def __traits__(gn3conn: gn3db.Connection, params: tuple[dict, ...]) -> tuple[dict, ...]:
+    """An internal utility function. Don't use outside of this module."""
+    if len(params) < 1:
+        return tuple()
+    paramstr = ", ".join(["(%s, %s, %s, %s)"] * len(params))
+    with gn3conn.cursor(DictCursor) as cursor:
+        cursor.execute(
+            "SELECT spc.SpeciesId, iset.InbredSetId, pf.Id AS PublishFreezeId, "
+            "pf.Name AS dataset_name, pf.FullName AS dataset_fullname, "
+            "pf.ShortName AS dataset_shortname, pxr.Id AS PublishXRefId "
+            "FROM "
+            "Species AS spc "
+            "INNER JOIN InbredSet AS iset "
+            "ON spc.SpeciesId=iset.SpeciesId "
+            "INNER JOIN PublishFreeze AS pf "
+            "ON iset.InbredSetId=pf.InbredSetId "
+            "INNER JOIN PublishXRef AS pxr "
+            "ON pf.InbredSetId=pxr.InbredSetId "
+            "WHERE (spc.SpeciesName, iset.InbredSetName, pf.Name, pxr.Id) "
+            f"IN ({paramstr})",
+            tuple(
+                itm for sublist in (
+                    (item["species"], item["group"], item["dataset"], item["name"])
+                    for item in params)
+                for itm in sublist))
+        return cursor.fetchall()
+
+@authorised_p(("system:data:link-to-group",),
+              error_description=(
+                  "You do not have sufficient privileges to link data to (a) "
+                  "group(s)."),
+              oauth2_scope="profile group resource")
+def link_phenotype_data(
+        authconn:authdb.DbConnection, gn3conn: gn3db.Connection, group: Group,
+        traits: tuple[dict, ...]) -> dict:
+    """Link phenotype traits to a user group."""
+    with authdb.cursor(authconn) as cursor:
+        params = tuple({
+            "data_link_id": str(uuid.uuid4()),
+            "group_id": str(group.group_id),
+            **item
+        } for item in __traits__(gn3conn, traits))
+        cursor.executemany(
+            "INSERT INTO linked_phenotype_data "
+            "VALUES ("
+            ":data_link_id, :group_id, :SpeciesId, :InbredSetId, "
+            ":PublishFreezeId, :dataset_name, :dataset_fullname, "
+            ":dataset_shortname, :PublishXRefId"
+            ")",
+            params)
+        return {
+            "description": (
+                f"Successfully linked {len(traits)} traits to group."),
+            "group": dictify(group),
+            "traits": params
+        }
diff --git a/gn_auth/auth/authorisation/data/views.py b/gn_auth/auth/authorisation/data/views.py
new file mode 100644
index 0000000..8adf862
--- /dev/null
+++ b/gn_auth/auth/authorisation/data/views.py
@@ -0,0 +1,310 @@
+"""Handle data endpoints."""
+import sys
+import uuid
+import json
+from typing import Any
+from functools import partial
+
+import redis
+from MySQLdb.cursors import DictCursor
+from authlib.integrations.flask_oauth2.errors import _HTTPException
+from flask import request, jsonify, Response, Blueprint, current_app as app
+
+import gn3.db_utils as gn3db
+from gn3 import jobs
+from gn3.commands import run_async_cmd
+from gn3.db.traits import build_trait_name
+
+from gn3.auth import db
+from gn3.auth.db_utils import with_db_connection
+
+from gn3.auth.authorisation.checks import require_json
+from gn3.auth.authorisation.errors import InvalidData, NotFoundError
+
+from gn3.auth.authorisation.groups.models import group_by_id
+
+from gn3.auth.authorisation.users.models import user_resource_roles
+
+from gn3.auth.authorisation.resources.checks import authorised_for
+from gn3.auth.authorisation.resources.models import (
+    user_resources, public_resources, attach_resources_data)
+
+from gn3.auth.authentication.users import User
+from gn3.auth.authentication.oauth2.resource_server import require_oauth
+
+from gn3.auth.authorisation.data.phenotypes import link_phenotype_data
+from gn3.auth.authorisation.data.mrna import link_mrna_data, ungrouped_mrna_data
+from gn3.auth.authorisation.data.genotypes import (
+    link_genotype_data, ungrouped_genotype_data)
+
+data = Blueprint("data", __name__)
+
+@data.route("species")
+def list_species() -> Response:
+    """List all available species information."""
+    with (gn3db.database_connection(app.config["SQL_URI"]) as gn3conn,
+          gn3conn.cursor(DictCursor) as cursor):
+        cursor.execute("SELECT * FROM Species")
+        return jsonify(tuple(dict(row) for row in cursor.fetchall()))
+
+@data.route("/authorisation", methods=["POST"])
+@require_json
+def authorisation() -> Response:
+    """Retrive the authorisation level for datasets/traits for the user."""
+    # Access endpoint with something like:
+    # curl -X POST http://127.0.0.1:8080/api/oauth2/data/authorisation \
+    #    -H "Content-Type: application/json" \
+    #    -d '{"traits": ["HC_M2_0606_P::1442370_at", "BXDGeno::01.001.695",
+    #        "BXDPublish::10001"]}'
+    db_uri = app.config["AUTH_DB"]
+    privileges = {}
+    user = User(uuid.uuid4(), "anon@ymous.user", "Anonymous User")
+    with db.connection(db_uri) as auth_conn:
+        try:
+            with require_oauth.acquire("profile group resource") as the_token:
+                user = the_token.user
+                resources = attach_resources_data(
+                    auth_conn, user_resources(auth_conn, the_token.user))
+                resources_roles = user_resource_roles(auth_conn, the_token.user)
+                privileges = {
+                    resource_id: tuple(
+                        privilege.privilege_id
+                        for roles in resources_roles[resource_id]
+                        for privilege in roles.privileges)#("group:resource:view-resource",)
+                    for resource_id, is_authorised
+                    in authorised_for(
+                        auth_conn, the_token.user,
+                        ("group:resource:view-resource",), tuple(
+                            resource.resource_id for resource in resources)).items()
+                    if is_authorised
+                }
+        except _HTTPException as exc:
+            err_msg = json.loads(exc.body)
+            if err_msg["error"] == "missing_authorization":
+                resources = attach_resources_data(
+                    auth_conn, public_resources(auth_conn))
+            else:
+                raise exc from None
+
+        def __gen_key__(resource, data_item):
+            if resource.resource_category.resource_category_key.lower() == "phenotype":
+                return (
+                    f"{resource.resource_category.resource_category_key.lower()}::"
+                    f"{data_item['dataset_name']}::{data_item['PublishXRefId']}")
+            return (
+                f"{resource.resource_category.resource_category_key.lower()}::"
+                f"{data_item['dataset_name']}")
+
+        data_to_resource_map = {
+            __gen_key__(resource, data_item): resource.resource_id
+            for resource in resources
+            for data_item in resource.resource_data
+        }
+        privileges = {
+            **{
+                resource.resource_id: ("system:resource:public-read",)
+                for resource in resources if resource.public
+            },
+            **privileges}
+
+        args = request.get_json()
+        traits_names = args["traits"] # type: ignore[index]
+        def __translate__(val):
+            return {
+                "Temp": "Temp",
+                "ProbeSet": "mRNA",
+                "Geno": "Genotype",
+                "Publish": "Phenotype"
+            }[val]
+
+        def __trait_key__(trait):
+            dataset_type = __translate__(trait['db']['dataset_type']).lower()
+            dataset_name = trait["db"]["dataset_name"]
+            if dataset_type == "phenotype":
+                return f"{dataset_type}::{dataset_name}::{trait['trait_name']}"
+            return f"{dataset_type}::{dataset_name}"
+
+        return jsonify(tuple(
+            {
+                "user": user._asdict(),
+                **{key:trait[key] for key in ("trait_fullname", "trait_name")},
+                "dataset_name": trait["db"]["dataset_name"],
+                "dataset_type": __translate__(trait["db"]["dataset_type"]),
+                "resource_id": data_to_resource_map.get(__trait_key__(trait)),
+                "privileges": privileges.get(
+                    data_to_resource_map.get(
+                        __trait_key__(trait),
+                        uuid.UUID("4afa415e-94cb-4189-b2c6-f9ce2b6a878d")),
+                    tuple()) + (
+                        # Temporary traits do not exist in db: Set them
+                        # as public-read
+                        ("system:resource:public-read",)
+                        if trait["db"]["dataset_type"] == "Temp"
+                        else tuple())
+            } for trait in
+            (build_trait_name(trait_fullname)
+             for trait_fullname in traits_names)))
+
+def __search_mrna__():
+    query = __request_key__("query", "")
+    limit = int(__request_key__("limit", 10000))
+    offset = int(__request_key__("offset", 0))
+    with gn3db.database_connection(app.config["SQL_URI"]) as gn3conn:
+        __ungrouped__ = partial(
+            ungrouped_mrna_data, gn3conn=gn3conn, search_query=query,
+            selected=__request_key_list__("selected"),
+            limit=limit, offset=offset)
+        return jsonify(with_db_connection(__ungrouped__))
+
+def __request_key__(key: str, default: Any = ""):
+    if bool(request.json):
+        return request.json.get(#type: ignore[union-attr]
+            key, request.args.get(key, request.form.get(key, default)))
+    return request.args.get(key, request.form.get(key, default))
+
+def __request_key_list__(key: str, default: tuple[Any, ...] = tuple()):
+    if bool(request.json):
+        return (request.json.get(key,[])#type: ignore[union-attr]
+                or request.args.getlist(key) or request.form.getlist(key)
+                or list(default))
+    return (request.args.getlist(key)
+            or request.form.getlist(key) or list(default))
+
+def __search_genotypes__():
+    query = __request_key__("query", "")
+    limit = int(__request_key__("limit", 10000))
+    offset = int(__request_key__("offset", 0))
+    with gn3db.database_connection(app.config["SQL_URI"]) as gn3conn:
+        __ungrouped__ = partial(
+            ungrouped_genotype_data, gn3conn=gn3conn, search_query=query,
+            selected=__request_key_list__("selected"),
+            limit=limit, offset=offset)
+        return jsonify(with_db_connection(__ungrouped__))
+
+def __search_phenotypes__():
+    # launch the external process to search for phenotypes
+    redisuri = app.config["REDIS_URI"]
+    with redis.Redis.from_url(redisuri, decode_responses=True) as redisconn:
+        job_id = uuid.uuid4()
+        selected = __request_key__("selected_traits", [])
+        command =[
+            sys.executable, "-m", "scripts.search_phenotypes",
+            __request_key__("species_name"),
+            __request_key__("query"),
+            str(job_id),
+            f"--host={__request_key__('gn3_server_uri')}",
+            f"--auth-db-uri={app.config['AUTH_DB']}",
+            f"--gn3-db-uri={app.config['SQL_URI']}",
+            f"--redis-uri={redisuri}",
+            f"--per-page={__request_key__('per_page')}"] +(
+                [f"--selected={json.dumps(selected)}"]
+                if len(selected) > 0 else [])
+        jobs.create_job(redisconn, {
+            "job_id": job_id, "command": command, "status": "queued",
+            "search_results": tuple()})
+        return jsonify({
+            "job_id": job_id,
+            "command_id": run_async_cmd(
+                redisconn, app.config.get("REDIS_JOB_QUEUE"), command),
+            "command": command
+        })
+
+@data.route("/search", methods=["GET"])
+@require_oauth("profile group resource")
+def search_unlinked_data():
+    """Search for various unlinked data."""
+    dataset_type = request.json["dataset_type"]
+    search_fns = {
+        "mrna": __search_mrna__,
+        "genotype": __search_genotypes__,
+        "phenotype": __search_phenotypes__
+    }
+    return search_fns[dataset_type]()
+
+@data.route("/search/phenotype/<uuid:job_id>", methods=["GET"])
+def pheno_search_results(job_id: uuid.UUID) -> Response:
+    """Get the search results from the external script"""
+    def __search_error__(err):
+        raise NotFoundError(err["error_description"])
+    redisuri = app.config["REDIS_URI"]
+    with redis.Redis.from_url(redisuri, decode_responses=True) as redisconn:
+        return jobs.job(redisconn, job_id).either(
+            __search_error__, jsonify)
+
+@data.route("/link/genotype", methods=["POST"])
+def link_genotypes() -> Response:
+    """Link genotype data to group."""
+    def __values__(form) -> dict[str, Any]:
+        if not bool(form.get("species_name", "").strip()):
+            raise InvalidData("Expected 'species_name' not provided.")
+        if not bool(form.get("group_id")):
+            raise InvalidData("Expected 'group_id' not provided.",)
+        try:
+            _group_id = uuid.UUID(form.get("group_id"))
+        except TypeError as terr:
+            raise InvalidData("Expected a UUID for 'group_id' value.") from terr
+        if not bool(form.get("selected")):
+            raise InvalidData("Expected at least one dataset to be provided.")
+        return {
+            "group_id": uuid.UUID(form.get("group_id")),
+            "datasets": form.get("selected")
+        }
+
+    def __link__(conn: db.DbConnection, group_id: uuid.UUID, datasets: dict):
+        return link_genotype_data(conn, group_by_id(conn, group_id), datasets)
+
+    return jsonify(with_db_connection(
+        partial(__link__, **__values__(request.json))))
+
+@data.route("/link/mrna", methods=["POST"])
+def link_mrna() -> Response:
+    """Link mrna data to group."""
+    def __values__(form) -> dict[str, Any]:
+        if not bool(form.get("species_name", "").strip()):
+            raise InvalidData("Expected 'species_name' not provided.")
+        if not bool(form.get("group_id")):
+            raise InvalidData("Expected 'group_id' not provided.",)
+        try:
+            _group_id = uuid.UUID(form.get("group_id"))
+        except TypeError as terr:
+            raise InvalidData("Expected a UUID for 'group_id' value.") from terr
+        if not bool(form.get("selected")):
+            raise InvalidData("Expected at least one dataset to be provided.")
+        return {
+            "group_id": uuid.UUID(form.get("group_id")),
+            "datasets": form.get("selected")
+        }
+
+    def __link__(conn: db.DbConnection, group_id: uuid.UUID, datasets: dict):
+        return link_mrna_data(conn, group_by_id(conn, group_id), datasets)
+
+    return jsonify(with_db_connection(
+        partial(__link__, **__values__(request.json))))
+
+@data.route("/link/phenotype", methods=["POST"])
+def link_phenotype() -> Response:
+    """Link phenotype data to group."""
+    def __values__(form):
+        if not bool(form.get("species_name", "").strip()):
+            raise InvalidData("Expected 'species_name' not provided.")
+        if not bool(form.get("group_id")):
+            raise InvalidData("Expected 'group_id' not provided.",)
+        try:
+            _group_id = uuid.UUID(form.get("group_id"))
+        except TypeError as terr:
+            raise InvalidData("Expected a UUID for 'group_id' value.") from terr
+        if not bool(form.get("selected")):
+            raise InvalidData("Expected at least one dataset to be provided.")
+        return {
+            "group_id": uuid.UUID(form["group_id"]),
+            "traits": form["selected"]
+        }
+
+    with gn3db.database_connection(app.config["SQL_URI"]) as gn3conn:
+        def __link__(conn: db.DbConnection, group_id: uuid.UUID,
+                     traits: tuple[dict, ...]) -> dict:
+            return link_phenotype_data(
+                conn, gn3conn, group_by_id(conn, group_id), traits)
+
+        return jsonify(with_db_connection(
+            partial(__link__, **__values__(request.json))))
diff --git a/gn_auth/auth/authorisation/errors.py b/gn_auth/auth/authorisation/errors.py
new file mode 100644
index 0000000..3bc7a04
--- /dev/null
+++ b/gn_auth/auth/authorisation/errors.py
@@ -0,0 +1,42 @@
+"""Authorisation exceptions"""
+
+class AuthorisationError(Exception):
+    """
+    Top-level exception for the `gn3.auth.authorisation` package.
+
+    All exceptions in this package should inherit from this class.
+    """
+    error_code: int = 400
+
+class ForbiddenAccess(AuthorisationError):
+    """Raised for forbidden access."""
+    error_code: int = 403
+
+class UserRegistrationError(AuthorisationError):
+    """Raised whenever a user registration fails"""
+
+class NotFoundError(AuthorisationError):
+    """Raised whenever we try fetching (a/an) object(s) that do(es) not exist."""
+    error_code: int = 404
+
+class InvalidData(AuthorisationError):
+    """
+    Exception if user requests invalid data
+    """
+    error_code: int = 400
+
+class InconsistencyError(AuthorisationError):
+    """
+    Exception raised due to data inconsistencies
+    """
+    error_code: int = 500
+
+class PasswordError(AuthorisationError):
+    """
+    Raise in case of an error with passwords.
+    """
+
+class UsernameError(AuthorisationError):
+    """
+    Raise in case of an error with a user's name.
+    """
diff --git a/gn_auth/auth/authorisation/groups/__init__.py b/gn_auth/auth/authorisation/groups/__init__.py
new file mode 100644
index 0000000..1cb0bba
--- /dev/null
+++ b/gn_auth/auth/authorisation/groups/__init__.py
@@ -0,0 +1,3 @@
+"""Initialise the `gn3.auth.authorisation.groups` package"""
+
+from .models import Group, GroupRole
diff --git a/gn_auth/auth/authorisation/groups/data.py b/gn_auth/auth/authorisation/groups/data.py
new file mode 100644
index 0000000..ee6f70e
--- /dev/null
+++ b/gn_auth/auth/authorisation/groups/data.py
@@ -0,0 +1,106 @@
+"""Handles the resource objects' data."""
+from MySQLdb.cursors import DictCursor
+
+from gn3 import db_utils as gn3db
+from gn3.auth import db as authdb
+from gn3.auth.authorisation.groups import Group
+from gn3.auth.authorisation.checks import authorised_p
+from gn3.auth.authorisation.errors import NotFoundError
+
+def __fetch_mrna_data_by_ids__(
+        conn: gn3db.Connection, dataset_ids: tuple[str, ...]) -> tuple[
+            dict, ...]:
+    """Fetch mRNA Assay data by ID."""
+    with conn.cursor(DictCursor) as cursor:
+        paramstr = ", ".join(["%s"] * len(dataset_ids))
+        cursor.execute(
+            "SELECT psf.Id, psf.Name AS dataset_name, "
+            "psf.FullName AS dataset_fullname, "
+            "ifiles.GN_AccesionId AS accession_id FROM ProbeSetFreeze AS psf "
+            "INNER JOIN InfoFiles AS ifiles ON psf.Name=ifiles.InfoPageName "
+            f"WHERE psf.Id IN ({paramstr})",
+            dataset_ids)
+        res = cursor.fetchall()
+        if res:
+            return tuple(dict(row) for row in res)
+        raise NotFoundError("Could not find mRNA Assay data with the given ID.")
+
+def __fetch_geno_data_by_ids__(
+        conn: gn3db.Connection, dataset_ids: tuple[str, ...]) -> tuple[
+            dict, ...]:
+    """Fetch genotype data by ID."""
+    with conn.cursor(DictCursor) as cursor:
+        paramstr = ", ".join(["%s"] * len(dataset_ids))
+        cursor.execute(
+            "SELECT gf.Id, gf.Name AS dataset_name, "
+            "gf.FullName AS dataset_fullname, "
+            "ifiles.GN_AccesionId AS accession_id FROM GenoFreeze AS gf "
+            "INNER JOIN InfoFiles AS ifiles ON gf.Name=ifiles.InfoPageName "
+            f"WHERE gf.Id IN ({paramstr})",
+            dataset_ids)
+        res = cursor.fetchall()
+        if res:
+            return tuple(dict(row) for row in res)
+        raise NotFoundError("Could not find Genotype data with the given ID.")
+
+def __fetch_pheno_data_by_ids__(
+        conn: gn3db.Connection, dataset_ids: tuple[str, ...]) -> tuple[
+            dict, ...]:
+    """Fetch phenotype data by ID."""
+    with conn.cursor(DictCursor) as cursor:
+        paramstr = ", ".join(["%s"] * len(dataset_ids))
+        cursor.execute(
+            "SELECT pxf.Id, iset.InbredSetName, pf.Id AS dataset_id, "
+            "pf.Name AS dataset_name, pf.FullName AS dataset_fullname, "
+            "ifiles.GN_AccesionId AS accession_id "
+            "FROM PublishXRef AS pxf "
+            "INNER JOIN InbredSet AS iset ON pxf.InbredSetId=iset.InbredSetId "
+            "INNER JOIN PublishFreeze AS pf ON iset.InbredSetId=pf.InbredSetId "
+            "INNER JOIN InfoFiles AS ifiles ON pf.Name=ifiles.InfoPageName "
+            f"WHERE pxf.Id IN ({paramstr})",
+            dataset_ids)
+        res = cursor.fetchall()
+        if res:
+            return tuple(dict(row) for row in res)
+        raise NotFoundError(
+            "Could not find Phenotype/Publish data with the given IDs.")
+
+def __fetch_data_by_id(
+        conn: gn3db.Connection, dataset_type: str,
+        dataset_ids: tuple[str, ...]) -> tuple[dict, ...]:
+    """Fetch data from MySQL by IDs."""
+    fetch_fns = {
+        "mrna": __fetch_mrna_data_by_ids__,
+        "genotype": __fetch_geno_data_by_ids__,
+        "phenotype": __fetch_pheno_data_by_ids__
+    }
+    return fetch_fns[dataset_type](conn, dataset_ids)
+
+@authorised_p(("system:data:link-to-group",),
+              error_description=(
+                  "You do not have sufficient privileges to link data to (a) "
+                  "group(s)."),
+              oauth2_scope="profile group resource")
+def link_data_to_group(
+        authconn: authdb.DbConnection, gn3conn: gn3db.Connection,
+        dataset_type: str, dataset_ids: tuple[str, ...], group: Group) -> tuple[
+            dict, ...]:
+    """Link the given data to the specified group."""
+    the_data = __fetch_data_by_id(gn3conn, dataset_type, dataset_ids)
+    with authdb.cursor(authconn) as cursor:
+        params = tuple({
+            "group_id": str(group.group_id), "dataset_type": {
+                "mrna": "mRNA", "genotype": "Genotype",
+                "phenotype": "Phenotype"
+            }[dataset_type],
+            "dataset_or_trait_id": item["Id"],
+            "dataset_name": item["dataset_name"],
+            "dataset_fullname": item["dataset_fullname"],
+            "accession_id": item["accession_id"]
+        } for item in the_data)
+        cursor.executemany(
+            "INSERT INTO linked_group_data VALUES"
+            "(:group_id, :dataset_type, :dataset_or_trait_id, :dataset_name, "
+            ":dataset_fullname, :accession_id)",
+            params)
+        return params
diff --git a/gn_auth/auth/authorisation/groups/models.py b/gn_auth/auth/authorisation/groups/models.py
new file mode 100644
index 0000000..5a3ae50
--- /dev/null
+++ b/gn_auth/auth/authorisation/groups/models.py
@@ -0,0 +1,400 @@
+"""Handle the management of resource/user groups."""
+import json
+from uuid import UUID, uuid4
+from functools import reduce
+from typing import Any, Sequence, Iterable, Optional, NamedTuple
+
+from flask import g
+from pymonad.maybe import Just, Maybe, Nothing
+
+from gn3.auth import db
+from gn3.auth.dictify import dictify
+from gn3.auth.authentication.users import User, user_by_id
+
+from ..checks import authorised_p
+from ..privileges import Privilege
+from ..errors import NotFoundError, AuthorisationError, InconsistencyError
+from ..roles.models import (
+    Role, create_role, check_user_editable, revoke_user_role_by_name,
+    assign_user_role_by_name)
+
+class Group(NamedTuple):
+    """Class representing a group."""
+    group_id: UUID
+    group_name: str
+    group_metadata: dict[str, Any]
+
+    def dictify(self):
+        """Return a dict representation of `Group` objects."""
+        return {
+            "group_id": self.group_id, "group_name": self.group_name,
+            "group_metadata": self.group_metadata
+        }
+
+DUMMY_GROUP = Group(
+    group_id=UUID("77cee65b-fe29-4383-ae41-3cb3b480cc70"),
+    group_name="GN3_DUMMY_GROUP",
+    group_metadata={
+        "group-description": "This is a dummy group to use as a placeholder"
+    })
+
+class GroupRole(NamedTuple):
+    """Class representing a role tied/belonging to a group."""
+    group_role_id: UUID
+    group: Group
+    role: Role
+
+    def dictify(self) -> dict[str, Any]:
+        """Return a dict representation of `GroupRole` objects."""
+        return {
+            "group_role_id": self.group_role_id, "group": dictify(self.group),
+            "role": dictify(self.role)
+        }
+
+class GroupCreationError(AuthorisationError):
+    """Raised whenever a group creation fails"""
+
+class MembershipError(AuthorisationError):
+    """Raised when there is an error with a user's membership to a group."""
+
+    def __init__(self, user: User, groups: Sequence[Group]):
+        """Initialise the `MembershipError` exception object."""
+        groups_str = ", ".join(group.group_name for group in groups)
+        error_description = (
+            f"User '{user.name} ({user.email})' is a member of {len(groups)} "
+            f"groups ({groups_str})")
+        super().__init__(f"{type(self).__name__}: {error_description}.")
+
+def user_membership(conn: db.DbConnection, user: User) -> Sequence[Group]:
+    """Returns all the groups that a member belongs to"""
+    query = (
+        "SELECT groups.group_id, group_name, groups.group_metadata "
+        "FROM group_users INNER JOIN groups "
+        "ON group_users.group_id=groups.group_id "
+        "WHERE group_users.user_id=?")
+    with db.cursor(conn) as cursor:
+        cursor.execute(query, (str(user.user_id),))
+        groups = tuple(Group(row[0], row[1], json.loads(row[2]))
+                       for row in cursor.fetchall())
+
+    return groups
+
+@authorised_p(
+    privileges = ("system:group:create-group",),
+    error_description = (
+        "You do not have the appropriate privileges to enable you to "
+        "create a new group."),
+    oauth2_scope = "profile group")
+def create_group(
+        conn: db.DbConnection, group_name: str, group_leader: User,
+        group_description: Optional[str] = None) -> Group:
+    """Create a new group."""
+    user_groups = user_membership(conn, group_leader)
+    if len(user_groups) > 0:
+        raise MembershipError(group_leader, user_groups)
+
+    with db.cursor(conn) as cursor:
+        new_group = save_group(
+            cursor, group_name,(
+                {"group_description": group_description}
+                if group_description else {}))
+        add_user_to_group(cursor, new_group, group_leader)
+        revoke_user_role_by_name(cursor, group_leader, "group-creator")
+        assign_user_role_by_name(cursor, group_leader, "group-leader")
+        return new_group
+
+@authorised_p(("group:role:create-role",),
+              error_description="Could not create the group role")
+def create_group_role(
+        conn: db.DbConnection, group: Group, role_name: str,
+        privileges: Iterable[Privilege]) -> GroupRole:
+    """Create a role attached to a group."""
+    with db.cursor(conn) as cursor:
+        group_role_id = uuid4()
+        role = create_role(cursor, role_name, privileges)
+        cursor.execute(
+            ("INSERT INTO group_roles(group_role_id, group_id, role_id) "
+             "VALUES(?, ?, ?)"),
+            (str(group_role_id), str(group.group_id), str(role.role_id)))
+
+    return GroupRole(group_role_id, group, role)
+
+def authenticated_user_group(conn) -> Maybe:
+    """
+    Returns the currently authenticated user's group.
+
+    Look into returning a Maybe object.
+    """
+    user = g.user
+    with db.cursor(conn) as cursor:
+        cursor.execute(
+            ("SELECT groups.* FROM group_users "
+             "INNER JOIN groups ON group_users.group_id=groups.group_id "
+             "WHERE group_users.user_id = ?"),
+            (str(user.user_id),))
+        groups = tuple(Group(UUID(row[0]), row[1], json.loads(row[2] or "{}"))
+                       for row in cursor.fetchall())
+
+    if len(groups) > 1:
+        raise MembershipError(user, groups)
+
+    if len(groups) == 1:
+        return Just(groups[0])
+
+    return Nothing
+
+def user_group(conn: db.DbConnection, user: User) -> Maybe[Group]:
+    """Returns the given user's group"""
+    with db.cursor(conn) as cursor:
+        cursor.execute(
+            ("SELECT groups.group_id, groups.group_name, groups.group_metadata "
+             "FROM group_users "
+             "INNER JOIN groups ON group_users.group_id=groups.group_id "
+             "WHERE group_users.user_id = ?"),
+            (str(user.user_id),))
+        groups = tuple(
+            Group(UUID(row[0]), row[1], json.loads(row[2] or "{}"))
+            for row in cursor.fetchall())
+
+        if len(groups) > 1:
+            raise MembershipError(user, groups)
+
+        if len(groups) == 1:
+            return Just(groups[0])
+
+    return Nothing
+
+def is_group_leader(conn: db.DbConnection, user: User, group: Group) -> bool:
+    """Check whether the given `user` is the leader of `group`."""
+
+    ugroup = user_group(conn, user).maybe(
+        False, lambda val: val) # type: ignore[arg-type, misc]
+    if not group:
+        # User cannot be a group leader if not a member of ANY group
+        return False
+
+    if not ugroup == group:
+        # User cannot be a group leader if not a member of THIS group
+        return False
+
+    with db.cursor(conn) as cursor:
+        cursor.execute(
+            ("SELECT roles.role_name FROM user_roles LEFT JOIN roles "
+             "ON user_roles.role_id = roles.role_id WHERE user_id = ?"),
+            (str(user.user_id),))
+        role_names = tuple(row[0] for row in cursor.fetchall())
+
+        return "group-leader" in role_names
+
+def all_groups(conn: db.DbConnection) -> Maybe[Sequence[Group]]:
+    """Retrieve all existing groups"""
+    with db.cursor(conn) as cursor:
+        cursor.execute("SELECT * FROM groups")
+        res = cursor.fetchall()
+        if res:
+            return Just(tuple(
+                Group(row["group_id"], row["group_name"],
+                      json.loads(row["group_metadata"])) for row in res))
+
+    return Nothing
+
+def save_group(
+        cursor: db.DbCursor, group_name: str,
+        group_metadata: dict[str, Any]) -> Group:
+    """Save a group to db"""
+    the_group = Group(uuid4(), group_name, group_metadata)
+    cursor.execute(
+        ("INSERT INTO groups "
+         "VALUES(:group_id, :group_name, :group_metadata) "
+         "ON CONFLICT (group_id) DO UPDATE SET "
+         "group_name=:group_name, group_metadata=:group_metadata"),
+    {"group_id": str(the_group.group_id), "group_name": the_group.group_name,
+     "group_metadata": json.dumps(the_group.group_metadata)})
+    return the_group
+
+def add_user_to_group(cursor: db.DbCursor, the_group: Group, user: User):
+    """Add `user` to `the_group` as a member."""
+    cursor.execute(
+        ("INSERT INTO group_users VALUES (:group_id, :user_id) "
+         "ON CONFLICT (group_id, user_id) DO NOTHING"),
+        {"group_id": str(the_group.group_id), "user_id": str(user.user_id)})
+
+@authorised_p(
+    privileges = ("system:group:view-group",),
+    error_description = (
+        "You do not have the appropriate privileges to access the list of users"
+        " in the group."))
+def group_users(conn: db.DbConnection, group_id: UUID) -> Iterable[User]:
+    """Retrieve all users that are members of group with id `group_id`."""
+    with db.cursor(conn) as cursor:
+        cursor.execute(
+            "SELECT u.* FROM group_users AS gu INNER JOIN users AS u "
+            "ON gu.user_id = u.user_id WHERE gu.group_id=:group_id",
+            {"group_id": str(group_id)})
+        results = cursor.fetchall()
+
+    return (User(UUID(row["user_id"]), row["email"], row["name"])
+            for row in results)
+
+@authorised_p(
+    privileges = ("system:group:view-group",),
+    error_description = (
+        "You do not have the appropriate privileges to access the group."))
+def group_by_id(conn: db.DbConnection, group_id: UUID) -> Group:
+    """Retrieve a group by its ID"""
+    with db.cursor(conn) as cursor:
+        cursor.execute("SELECT * FROM groups WHERE group_id=:group_id",
+                       {"group_id": str(group_id)})
+        row = cursor.fetchone()
+        if row:
+            return Group(
+                UUID(row["group_id"]),
+                row["group_name"],
+                json.loads(row["group_metadata"]))
+
+    raise NotFoundError(f"Could not find group with ID '{group_id}'.")
+
+@authorised_p(("system:group:view-group", "system:group:edit-group"),
+              error_description=("You do not have the appropriate authorisation"
+                                 " to act upon the join requests."),
+              oauth2_scope="profile group")
+def join_requests(conn: db.DbConnection, user: User):
+    """List all the join requests for the user's group."""
+    with db.cursor(conn) as cursor:
+        group = user_group(conn, user).maybe(DUMMY_GROUP, lambda grp: grp)# type: ignore[misc]
+        if group != DUMMY_GROUP and is_group_leader(conn, user, group):
+            cursor.execute(
+                "SELECT gjr.*, u.email, u.name FROM group_join_requests AS gjr "
+                "INNER JOIN users AS u ON gjr.requester_id=u.user_id "
+                "WHERE gjr.group_id=? AND gjr.status='PENDING'",
+                (str(group.group_id),))
+            return tuple(dict(row)for row in cursor.fetchall())
+
+    raise AuthorisationError(
+        "You do not have the appropriate authorisation to access the "
+        "group's join requests.")
+
+@authorised_p(("system:group:view-group", "system:group:edit-group"),
+              error_description=("You do not have the appropriate authorisation"
+                                 " to act upon the join requests."),
+              oauth2_scope="profile group")
+def accept_reject_join_request(
+        conn: db.DbConnection, request_id: UUID, user: User, status: str) -> dict:
+    """Accept/Reject a join request."""
+    assert status in ("ACCEPTED", "REJECTED"), f"Invalid status '{status}'."
+    with db.cursor(conn) as cursor:
+        group = user_group(conn, user).maybe(DUMMY_GROUP, lambda grp: grp) # type: ignore[misc]
+        cursor.execute("SELECT * FROM group_join_requests WHERE request_id=?",
+                       (str(request_id),))
+        row = cursor.fetchone()
+        if row:
+            if group.group_id == UUID(row["group_id"]):
+                try:
+                    the_user = user_by_id(conn, UUID(row["requester_id"]))
+                    if status == "ACCEPTED":
+                        add_user_to_group(cursor, group, the_user)
+                        revoke_user_role_by_name(cursor, the_user, "group-creator")
+                    cursor.execute(
+                        "UPDATE group_join_requests SET status=? "
+                        "WHERE request_id=?",
+                        (status, str(request_id)))
+                    return {"request_id": request_id, "status": status}
+                except NotFoundError as nfe:
+                    raise InconsistencyError(
+                        "Could not find user associated with join request."
+                    ) from nfe
+            raise AuthorisationError(
+                "You cannot act on other groups join requests")
+        raise NotFoundError(f"Could not find request with ID '{request_id}'")
+
+def __organise_privileges__(acc, row):
+    role_id = UUID(row["role_id"])
+    role = acc.get(role_id, False)
+    if role:
+        return {
+            **acc,
+            role_id: Role(
+                role.role_id, role.role_name,
+                bool(int(row["user_editable"])),
+                role.privileges + (
+                    Privilege(row["privilege_id"],
+                              row["privilege_description"]),))
+        }
+    return {
+        **acc,
+        role_id: Role(
+            UUID(row["role_id"]), row["role_name"],
+            bool(int(row["user_editable"])),
+            (Privilege(row["privilege_id"], row["privilege_description"]),))
+    }
+
+# @authorised_p(("group:role:view",),
+#               "Insufficient privileges to view role",
+#               oauth2_scope="profile group role")
+def group_role_by_id(
+        conn: db.DbConnection, group: Group, group_role_id: UUID) -> GroupRole:
+    """Retrieve GroupRole from id by its `group_role_id`."""
+    ## TODO: do privileges check before running actual query
+    ##       the check commented out above doesn't work correctly
+    with db.cursor(conn) as cursor:
+        cursor.execute(
+            "SELECT gr.group_role_id, r.*, p.* "
+            "FROM group_roles AS gr "
+            "INNER JOIN roles AS r ON gr.role_id=r.role_id "
+            "INNER JOIN role_privileges AS rp ON rp.role_id=r.role_id "
+            "INNER JOIN privileges AS p ON p.privilege_id=rp.privilege_id "
+            "WHERE gr.group_role_id=? AND gr.group_id=?",
+            (str(group_role_id), str(group.group_id)))
+        rows = cursor.fetchall()
+        if rows:
+            roles: tuple[Role,...] = tuple(reduce(
+                __organise_privileges__, rows, {}).values())
+            assert len(roles) == 1
+            return GroupRole(group_role_id, group, roles[0])
+        raise NotFoundError(
+            f"Group role with ID '{group_role_id}' does not exist.")
+
+@authorised_p(("group:role:edit-role",),
+              "You do not have the privilege to edit a role.",
+              oauth2_scope="profile group role")
+def add_privilege_to_group_role(conn: db.DbConnection, group_role: GroupRole,
+                                privilege: Privilege) -> GroupRole:
+    """Add `privilege` to `group_role`."""
+    ## TODO: do privileges check.
+    check_user_editable(group_role.role)
+    with db.cursor(conn) as cursor:
+        cursor.execute(
+            "INSERT INTO role_privileges(role_id,privilege_id) "
+            "VALUES (?, ?) ON CONFLICT (role_id, privilege_id) "
+            "DO NOTHING",
+            (str(group_role.role.role_id), str(privilege.privilege_id)))
+        return GroupRole(
+            group_role.group_role_id,
+            group_role.group,
+            Role(group_role.role.role_id,
+                 group_role.role.role_name,
+                 group_role.role.user_editable,
+                 group_role.role.privileges + (privilege,)))
+
+@authorised_p(("group:role:edit-role",),
+              "You do not have the privilege to edit a role.",
+              oauth2_scope="profile group role")
+def delete_privilege_from_group_role(
+        conn: db.DbConnection, group_role: GroupRole,
+        privilege: Privilege) -> GroupRole:
+    """Delete `privilege` to `group_role`."""
+    ## TODO: do privileges check.
+    check_user_editable(group_role.role)
+    with db.cursor(conn) as cursor:
+        cursor.execute(
+            "DELETE FROM role_privileges WHERE "
+            "role_id=? AND privilege_id=?",
+            (str(group_role.role.role_id), str(privilege.privilege_id)))
+        return GroupRole(
+            group_role.group_role_id,
+            group_role.group,
+            Role(group_role.role.role_id,
+                 group_role.role.role_name,
+                 group_role.role.user_editable,
+                 tuple(priv for priv in group_role.role.privileges
+                       if priv != privilege)))
diff --git a/gn_auth/auth/authorisation/groups/views.py b/gn_auth/auth/authorisation/groups/views.py
new file mode 100644
index 0000000..628df36
--- /dev/null
+++ b/gn_auth/auth/authorisation/groups/views.py
@@ -0,0 +1,431 @@
+"""The views/routes for the `gn3.auth.authorisation.groups` package."""
+import uuid
+import datetime
+from typing import Iterable
+from functools import partial
+
+from MySQLdb.cursors import DictCursor
+from flask import request, jsonify, Response, Blueprint, current_app
+
+from gn3.auth import db
+from gn3 import db_utils as gn3db
+
+from gn3.auth.dictify import dictify
+from gn3.auth.db_utils import with_db_connection
+
+from .data import link_data_to_group
+from .models import (
+    Group, user_group, all_groups, DUMMY_GROUP, GroupRole, group_by_id,
+    join_requests, group_role_by_id, GroupCreationError,
+    accept_reject_join_request, group_users as _group_users,
+    create_group as _create_group, add_privilege_to_group_role,
+    delete_privilege_from_group_role, create_group_role as _create_group_role)
+
+from ..roles.models import Role
+from ..roles.models import user_roles
+
+from ..checks import authorised_p
+from ..privileges import Privilege, privileges_by_ids
+from ..errors import InvalidData, NotFoundError, AuthorisationError
+
+from ...authentication.users import User
+from ...authentication.oauth2.resource_server import require_oauth
+
+groups = Blueprint("groups", __name__)
+
+@groups.route("/list", methods=["GET"])
+@require_oauth("profile group")
+def list_groups():
+    """Return the list of groups that exist."""
+    with db.connection(current_app.config["AUTH_DB"]) as conn:
+        the_groups = all_groups(conn)
+
+    return jsonify(the_groups.maybe(
+        [], lambda grps: [dictify(grp) for grp in grps]))
+
+@groups.route("/create", methods=["POST"])
+@require_oauth("profile group")
+def create_group():
+    """Create a new group."""
+    with require_oauth.acquire("profile group") as the_token:
+        group_name=request.form.get("group_name", "").strip()
+        if not bool(group_name):
+            raise GroupCreationError("Could not create the group.")
+
+        db_uri = current_app.config["AUTH_DB"]
+        with db.connection(db_uri) as conn:
+            user = the_token.user
+            new_group = _create_group(
+                conn, group_name, user, request.form.get("group_description"))
+            return jsonify({
+                **dictify(new_group), "group_leader": dictify(user)
+            })
+
+@groups.route("/members/<uuid:group_id>", methods=["GET"])
+@require_oauth("profile group")
+def group_members(group_id: uuid.UUID) -> Response:
+    """Retrieve all the members of a group."""
+    with require_oauth.acquire("profile group") as the_token:# pylint: disable=[unused-variable]
+        db_uri = current_app.config["AUTH_DB"]
+        ## Check that user has appropriate privileges and remove the pylint disable above
+        with db.connection(db_uri) as conn:
+            return jsonify(tuple(
+                dictify(user) for user in _group_users(conn, group_id)))
+
+@groups.route("/requests/join/<uuid:group_id>", methods=["POST"])
+@require_oauth("profile group")
+def request_to_join(group_id: uuid.UUID) -> Response:
+    """Request to join a group."""
+    def __request__(conn: db.DbConnection, user: User, group_id: uuid.UUID,
+                    message: str):
+        with db.cursor(conn) as cursor:
+            group = user_group(conn, user).maybe(# type: ignore[misc]
+                False, lambda grp: grp)# type: ignore[arg-type]
+            if group:
+                error = AuthorisationError(
+                    "You cannot request to join a new group while being a "
+                    "member of an existing group.")
+                error.error_code = 400
+                raise error
+            request_id = uuid.uuid4()
+            cursor.execute(
+                "INSERT INTO group_join_requests VALUES "
+                "(:request_id, :group_id, :user_id, :ts, :status, :msg)",
+                {
+                    "request_id": str(request_id),
+                    "group_id": str(group_id),
+                    "user_id": str(user.user_id),
+                    "ts": datetime.datetime.now().timestamp(),
+                    "status": "PENDING",
+                    "msg": message
+                })
+            return {
+                "request_id":  request_id,
+                "message": "Successfully sent the join request."
+            }
+
+    with require_oauth.acquire("profile group") as the_token:
+        form = request.form
+        results = with_db_connection(partial(
+            __request__, user=the_token.user, group_id=group_id, message=form.get(
+                "message", "I hereby request that you add me to your group.")))
+        return jsonify(results)
+
+@groups.route("/requests/join/list", methods=["GET"])
+@require_oauth("profile group")
+def list_join_requests() -> Response:
+    """List the pending join requests."""
+    with require_oauth.acquire("profile group") as the_token:
+        return jsonify(with_db_connection(partial(
+            join_requests, user=the_token.user)))
+
+@groups.route("/requests/join/accept", methods=["POST"])
+@require_oauth("profile group")
+def accept_join_requests() -> Response:
+    """Accept a join request."""
+    with require_oauth.acquire("profile group") as the_token:
+        form = request.form
+        request_id = uuid.UUID(form.get("request_id"))
+        return jsonify(with_db_connection(partial(
+            accept_reject_join_request, request_id=request_id,
+            user=the_token.user, status="ACCEPTED")))
+
+@groups.route("/requests/join/reject", methods=["POST"])
+@require_oauth("profile group")
+def reject_join_requests() -> Response:
+    """Reject a join request."""
+    with require_oauth.acquire("profile group") as the_token:
+        form = request.form
+        request_id = uuid.UUID(form.get("request_id"))
+        return jsonify(with_db_connection(partial(
+            accept_reject_join_request, request_id=request_id,
+            user=the_token.user, status="REJECTED")))
+
+def unlinked_mrna_data(
+        conn: db.DbConnection, group: Group) -> tuple[dict, ...]:
+    """
+    Retrieve all mRNA Assay data linked to a group but not linked to any
+    resource.
+    """
+    query = (
+        "SELECT lmd.* FROM linked_mrna_data lmd "
+        "LEFT JOIN mrna_resources mr ON lmd.data_link_id=mr.data_link_id "
+        "WHERE lmd.group_id=? AND mr.data_link_id IS NULL")
+    with db.cursor(conn) as cursor:
+        cursor.execute(query, (str(group.group_id),))
+        return tuple(dict(row) for row in cursor.fetchall())
+
+def unlinked_genotype_data(
+        conn: db.DbConnection, group: Group) -> tuple[dict, ...]:
+    """
+    Retrieve all genotype data linked to a group but not linked to any resource.
+    """
+    query = (
+        "SELECT lgd.* FROM linked_genotype_data lgd "
+        "LEFT JOIN genotype_resources gr ON lgd.data_link_id=gr.data_link_id "
+        "WHERE lgd.group_id=? AND gr.data_link_id IS NULL")
+    with db.cursor(conn) as cursor:
+        cursor.execute(query, (str(group.group_id),))
+        return tuple(dict(row) for row in cursor.fetchall())
+
+def unlinked_phenotype_data(
+        authconn: db.DbConnection, gn3conn: gn3db.Connection,
+        group: Group) -> tuple[dict, ...]:
+    """
+    Retrieve all phenotype data linked to a group but not linked to any
+    resource.
+    """
+    with db.cursor(authconn) as authcur, gn3conn.cursor(DictCursor) as gn3cur:
+        authcur.execute(
+            "SELECT lpd.* FROM linked_phenotype_data AS lpd "
+            "LEFT JOIN phenotype_resources AS pr "
+            "ON lpd.data_link_id=pr.data_link_id "
+            "WHERE lpd.group_id=? AND pr.data_link_id IS NULL",
+            (str(group.group_id),))
+        results = authcur.fetchall()
+        ids: dict[tuple[str, ...], str] = {
+            (
+                row["SpeciesId"], row["InbredSetId"], row["PublishFreezeId"],
+                row["PublishXRefId"]): row["data_link_id"]
+            for row in results
+        }
+        if len(ids.keys()) < 1:
+            return tuple()
+        paramstr = ", ".join(["(%s, %s, %s, %s)"] * len(ids.keys()))
+        gn3cur.execute(
+            "SELECT spc.SpeciesId, spc.SpeciesName, iset.InbredSetId, "
+            "iset.InbredSetName, pf.Id AS PublishFreezeId, "
+            "pf.Name AS dataset_name, pf.FullName AS dataset_fullname, "
+            "pf.ShortName AS dataset_shortname, pxr.Id AS PublishXRefId, "
+            "pub.PubMed_ID, pub.Title, pub.Year, "
+            "phen.Pre_publication_description, "
+            "phen.Post_publication_description, phen.Original_description "
+            "FROM "
+            "Species AS spc "
+            "INNER JOIN InbredSet AS iset "
+            "ON spc.SpeciesId=iset.SpeciesId "
+            "INNER JOIN PublishFreeze AS pf "
+            "ON iset.InbredSetId=pf.InbredSetId "
+            "INNER JOIN PublishXRef AS pxr "
+            "ON pf.InbredSetId=pxr.InbredSetId "
+            "INNER JOIN Publication AS pub "
+            "ON pxr.PublicationId=pub.Id "
+            "INNER JOIN Phenotype AS phen "
+            "ON pxr.PhenotypeId=phen.Id "
+            "WHERE (spc.SpeciesId, iset.InbredSetId, pf.Id, pxr.Id) "
+            f"IN ({paramstr})",
+            tuple(item for sublist in ids.keys() for item in sublist))
+        return tuple({
+            **{key: value for key, value in row.items() if key not in
+               ("Post_publication_description", "Pre_publication_description",
+                "Original_description")},
+            "description": (
+                row["Post_publication_description"] or
+                row["Pre_publication_description"] or
+                row["Original_description"]),
+            "data_link_id": ids[tuple(str(row[key]) for key in (
+                "SpeciesId", "InbredSetId", "PublishFreezeId",
+                "PublishXRefId"))]
+        } for row in gn3cur.fetchall())
+
+@groups.route("/<string:resource_type>/unlinked-data")
+@require_oauth("profile group resource")
+def unlinked_data(resource_type: str) -> Response:
+    """View data linked to the group but not linked to any resource."""
+    if resource_type not in ("all", "mrna", "genotype", "phenotype"):
+        raise AuthorisationError(f"Invalid resource type {resource_type}")
+
+    with require_oauth.acquire("profile group resource") as the_token:
+        db_uri = current_app.config["AUTH_DB"]
+        gn3db_uri = current_app.config["SQL_URI"]
+        with (db.connection(db_uri) as authconn,
+              gn3db.database_connection(gn3db_uri) as gn3conn):
+            ugroup = user_group(authconn, the_token.user).maybe(# type: ignore[misc]
+                DUMMY_GROUP, lambda grp: grp)
+            if ugroup == DUMMY_GROUP:
+                return jsonify(tuple())
+
+            unlinked_fns = {
+                "mrna": unlinked_mrna_data,
+                "genotype": unlinked_genotype_data,
+                "phenotype": lambda conn, grp: partial(
+                    unlinked_phenotype_data, gn3conn=gn3conn)(
+                        authconn=conn, group=grp)
+            }
+            return jsonify(tuple(
+                dict(row) for row in unlinked_fns[resource_type](
+                    authconn, ugroup)))
+
+    return jsonify(tuple())
+
+@groups.route("/data/link", methods=["POST"])
+@require_oauth("profile group resource")
+def link_data() -> Response:
+    """Link selected data to specified group."""
+    with require_oauth.acquire("profile group resource") as _the_token:
+        form = request.form
+        group_id = uuid.UUID(form["group_id"])
+        dataset_ids = form.getlist("dataset_ids")
+        dataset_type = form.get("dataset_type")
+        if dataset_type not in ("mrna", "genotype", "phenotype"):
+            raise InvalidData("Unexpected dataset type requested!")
+        def __link__(conn: db.DbConnection):
+            group = group_by_id(conn, group_id)
+            with gn3db.database_connection(current_app.config["SQL_URI"]) as gn3conn:
+                return link_data_to_group(
+                    conn, gn3conn, dataset_type, dataset_ids, group)
+
+        return jsonify(with_db_connection(__link__))
+
+@groups.route("/roles", methods=["GET"])
+@require_oauth("profile group")
+def group_roles():
+    """Return a list of all available group roles."""
+    with require_oauth.acquire("profile group role") as the_token:
+        def __list_roles__(conn: db.DbConnection):
+            ## TODO: Check that user has appropriate privileges
+            with db.cursor(conn) as cursor:
+                group = user_group(conn, the_token.user).maybe(# type: ignore[misc]
+                    DUMMY_GROUP, lambda grp: grp)
+                if group == DUMMY_GROUP:
+                    return tuple()
+                cursor.execute(
+                    "SELECT gr.group_role_id, r.* "
+                    "FROM group_roles AS gr INNER JOIN roles AS r "
+                    "ON gr.role_id=r.role_id "
+                    "WHERE group_id=?",
+                    (str(group.group_id),))
+                return tuple(
+                    GroupRole(uuid.UUID(row["group_role_id"]),
+                              group,
+                              Role(uuid.UUID(row["role_id"]),
+                                   row["role_name"],
+                                   bool(int(row["user_editable"])),
+                                   tuple()))
+                    for row in cursor.fetchall())
+        return jsonify(tuple(
+            dictify(role) for role in with_db_connection(__list_roles__)))
+
+@groups.route("/privileges", methods=["GET"])
+@require_oauth("profile group")
+def group_privileges():
+    """Return a list of all available group roles."""
+    with require_oauth.acquire("profile group role") as the_token:
+        def __list_privileges__(conn: db.DbConnection) -> Iterable[Privilege]:
+            ## TODO: Check that user has appropriate privileges
+            this_user_roles = user_roles(conn, the_token.user)
+            with db.cursor(conn) as cursor:
+                cursor.execute("SELECT * FROM privileges "
+                               "WHERE privilege_id LIKE 'group:%'")
+                group_level_roles = tuple(
+                    Privilege(row["privilege_id"], row["privilege_description"])
+                    for row in cursor.fetchall())
+            return tuple(privilege for arole in this_user_roles
+                         for privilege in arole.privileges) + group_level_roles
+        return jsonify(tuple(
+            dictify(priv) for priv in with_db_connection(__list_privileges__)))
+
+
+
+@groups.route("/role/create", methods=["POST"])
+@require_oauth("profile group")
+def create_group_role():
+    """Create a new group role."""
+    with require_oauth.acquire("profile group role") as the_token:
+        ## TODO: Check that user has appropriate privileges
+        @authorised_p(("group:role:create-role",),
+                      "You do not have the privilege to create new roles",
+                      oauth2_scope="profile group role")
+        def __create__(conn: db.DbConnection) -> GroupRole:
+            ## TODO: Check user cannot assign any privilege they don't have.
+            form = request.form
+            role_name = form.get("role_name", "").strip()
+            privileges_ids = form.getlist("privileges[]")
+            if len(role_name) == 0:
+                raise InvalidData("Role name not provided!")
+            if len(privileges_ids) == 0:
+                raise InvalidData(
+                    "At least one privilege needs to be provided.")
+
+            group = user_group(conn, the_token.user).maybe(# type: ignore[misc]
+                    DUMMY_GROUP, lambda grp: grp)
+
+            if group == DUMMY_GROUP:
+                raise AuthorisationError(
+                    "A user without a group cannot create a new role.")
+            privileges = privileges_by_ids(conn, tuple(privileges_ids))
+            if len(privileges_ids) != len(privileges):
+                raise InvalidData(
+                    f"{len(privileges_ids) - len(privileges)} of the selected "
+                    "privileges were not found in the database.")
+
+            return _create_group_role(conn, group, role_name, privileges)
+
+        return jsonify(with_db_connection(__create__))
+
+@groups.route("/role/<uuid:group_role_id>", methods=["GET"])
+@require_oauth("profile group")
+def view_group_role(group_role_id: uuid.UUID):
+    """Return the details of the given role."""
+    with require_oauth.acquire("profile group role") as the_token:
+        def __group_role__(conn: db.DbConnection) -> GroupRole:
+            group = user_group(conn, the_token.user).maybe(#type: ignore[misc]
+                DUMMY_GROUP, lambda grp: grp)
+
+            if group == DUMMY_GROUP:
+                raise AuthorisationError(
+                    "A user without a group cannot view group roles.")
+            return group_role_by_id(conn, group, group_role_id)
+        return jsonify(dictify(with_db_connection(__group_role__)))
+
+def __add_remove_priv_to_from_role__(conn: db.DbConnection,
+                                     group_role_id: uuid.UUID,
+                                     direction: str,
+                                     user: User) -> GroupRole:
+    assert direction in ("ADD", "DELETE")
+    group = user_group(conn, user).maybe(# type: ignore[misc]
+        DUMMY_GROUP, lambda grp: grp)
+
+    if group == DUMMY_GROUP:
+        raise AuthorisationError(
+            "You need to be a member of a group to edit roles.")
+    try:
+        privilege_id = request.form.get("privilege_id", "")
+        assert bool(privilege_id), "Privilege to add must be provided."
+        privileges = privileges_by_ids(conn, (privilege_id,))
+        if len(privileges) == 0:
+            raise NotFoundError("Privilege not found.")
+        dir_fns = {
+            "ADD": add_privilege_to_group_role,
+            "DELETE": delete_privilege_from_group_role
+        }
+        return dir_fns[direction](
+            conn,
+            group_role_by_id(conn, group, group_role_id),
+            privileges[0])
+    except AssertionError as aerr:
+        raise InvalidData(aerr.args[0]) from aerr
+
+@groups.route("/role/<uuid:group_role_id>/privilege/add", methods=["POST"])
+@require_oauth("profile group")
+def add_priv_to_role(group_role_id: uuid.UUID) -> Response:
+    """Add privilege to group role."""
+    with require_oauth.acquire("profile group role") as the_token:
+        return jsonify({
+            **dictify(with_db_connection(partial(
+                __add_remove_priv_to_from_role__, group_role_id=group_role_id,
+                direction="ADD", user=the_token.user))),
+            "description": "Privilege added successfully"
+        })
+
+@groups.route("/role/<uuid:group_role_id>/privilege/delete", methods=["POST"])
+@require_oauth("profile group")
+def delete_priv_from_role(group_role_id: uuid.UUID) -> Response:
+    """Delete privilege from group role."""
+    with require_oauth.acquire("profile group role") as the_token:
+        return jsonify({
+            **dictify(with_db_connection(partial(
+                __add_remove_priv_to_from_role__, group_role_id=group_role_id,
+                direction="DELETE", user=the_token.user))),
+            "description": "Privilege deleted successfully"
+        })
diff --git a/gn_auth/auth/authorisation/privileges.py b/gn_auth/auth/authorisation/privileges.py
new file mode 100644
index 0000000..dbb4129
--- /dev/null
+++ b/gn_auth/auth/authorisation/privileges.py
@@ -0,0 +1,47 @@
+"""Handle privileges"""
+from typing import Any, Iterable, NamedTuple
+
+from gn3.auth import db
+from gn3.auth.authentication.users import User
+
+class Privilege(NamedTuple):
+    """Class representing a privilege: creates immutable objects."""
+    privilege_id: str
+    privilege_description: str
+
+    def dictify(self) -> dict[str, Any]:
+        """Return a dict representation of `Privilege` objects."""
+        return {
+            "privilege_id": self.privilege_id,
+            "privilege_description": self.privilege_description
+        }
+
+def user_privileges(conn: db.DbConnection, user: User) -> Iterable[Privilege]:
+    """Fetch the user's privileges from the database."""
+    with db.cursor(conn) as cursor:
+        cursor.execute(
+            ("SELECT p.privilege_id, p.privilege_description "
+             "FROM user_roles AS ur "
+             "INNER JOIN role_privileges AS rp ON ur.role_id=rp.role_id "
+             "INNER JOIN privileges AS p ON rp.privilege_id=p.privilege_id "
+             "WHERE ur.user_id=?"),
+            (str(user.user_id),))
+        results = cursor.fetchall()
+
+    return (Privilege(row[0], row[1]) for row in results)
+
+def privileges_by_ids(
+        conn: db.DbConnection, privileges_ids: tuple[str, ...]) -> tuple[
+            Privilege, ...]:
+    """Fetch privileges by their ids."""
+    if len(privileges_ids) == 0:
+        return tuple()
+
+    with db.cursor(conn) as cursor:
+        clause = ", ".join(["?"] * len(privileges_ids))
+        cursor.execute(
+            f"SELECT * FROM privileges WHERE privilege_id IN ({clause})",
+            privileges_ids)
+        return tuple(
+            Privilege(row["privilege_id"], row["privilege_description"])
+            for row in cursor.fetchall())
diff --git a/gn_auth/auth/authorisation/resources/__init__.py b/gn_auth/auth/authorisation/resources/__init__.py
new file mode 100644
index 0000000..869ab60
--- /dev/null
+++ b/gn_auth/auth/authorisation/resources/__init__.py
@@ -0,0 +1,2 @@
+"""Initialise the `gn3.auth.authorisation.resources` package."""
+from .models import Resource, ResourceCategory
diff --git a/gn_auth/auth/authorisation/resources/checks.py b/gn_auth/auth/authorisation/resources/checks.py
new file mode 100644
index 0000000..fafde76
--- /dev/null
+++ b/gn_auth/auth/authorisation/resources/checks.py
@@ -0,0 +1,47 @@
+"""Handle authorisation checks for resources"""
+from uuid import UUID
+from functools import reduce
+from typing import Sequence
+
+from gn3.auth import db
+from gn3.auth.authentication.users import User
+
+def __organise_privileges_by_resource_id__(rows):
+    def __organise__(privs, row):
+        resource_id = UUID(row["resource_id"])
+        return {
+            **privs,
+            resource_id: (row["privilege_id"],) + privs.get(
+                resource_id, tuple())
+        }
+    return reduce(__organise__, rows, {})
+
+def authorised_for(conn: db.DbConnection, user: User, privileges: tuple[str],
+                   resource_ids: Sequence[UUID]) -> dict[UUID, bool]:
+    """
+    Check whether `user` is authorised to access `resources` according to given
+    `privileges`.
+    """
+    with db.cursor(conn) as cursor:
+        cursor.execute(
+            ("SELECT guror.*, rp.privilege_id FROM "
+             "group_user_roles_on_resources AS guror "
+             "INNER JOIN group_roles AS gr ON  "
+             "(guror.group_id=gr.group_id AND guror.role_id=gr.role_id) "
+             "INNER JOIN roles AS r ON gr.role_id=r.role_id "
+             "INNER JOIN role_privileges AS rp ON r.role_id=rp.role_id "
+             "WHERE guror.user_id=? "
+             f"AND guror.resource_id IN ({', '.join(['?']*len(resource_ids))})"
+             f"AND rp.privilege_id IN ({', '.join(['?']*len(privileges))})"),
+            ((str(user.user_id),) + tuple(
+                str(r_id) for r_id in resource_ids) + tuple(privileges)))
+        resource_privileges = __organise_privileges_by_resource_id__(
+            cursor.fetchall())
+        authorised = tuple(resource_id for resource_id, res_privileges
+                           in resource_privileges.items()
+                           if all(priv in res_privileges
+                                  for priv in privileges))
+        return {
+            resource_id: resource_id in authorised
+            for resource_id in resource_ids
+        }
diff --git a/gn_auth/auth/authorisation/resources/models.py b/gn_auth/auth/authorisation/resources/models.py
new file mode 100644
index 0000000..b301a93
--- /dev/null
+++ b/gn_auth/auth/authorisation/resources/models.py
@@ -0,0 +1,579 @@
+"""Handle the management of resources."""
+import json
+import sqlite3
+from uuid import UUID, uuid4
+from functools import reduce, partial
+from typing import Any, Dict, Sequence, Optional, NamedTuple
+
+from gn3.auth import db
+from gn3.auth.dictify import dictify
+from gn3.auth.authentication.users import User
+from gn3.auth.db_utils import with_db_connection
+
+from .checks import authorised_for
+
+from ..checks import authorised_p
+from ..errors import NotFoundError, AuthorisationError
+from ..groups.models import (
+    Group, GroupRole, user_group, group_by_id, is_group_leader)
+
+class MissingGroupError(AuthorisationError):
+    """Raised for any resource operation without a group."""
+
+class ResourceCategory(NamedTuple):
+    """Class representing a resource category."""
+    resource_category_id: UUID
+    resource_category_key: str
+    resource_category_description: str
+
+    def dictify(self) -> dict[str, Any]:
+        """Return a dict representation of `ResourceCategory` objects."""
+        return {
+            "resource_category_id": self.resource_category_id,
+            "resource_category_key": self.resource_category_key,
+            "resource_category_description": self.resource_category_description
+        }
+
+class Resource(NamedTuple):
+    """Class representing a resource."""
+    group: Group
+    resource_id: UUID
+    resource_name: str
+    resource_category: ResourceCategory
+    public: bool
+    resource_data: Sequence[dict[str, Any]] = tuple()
+
+    def dictify(self) -> dict[str, Any]:
+        """Return a dict representation of `Resource` objects."""
+        return {
+            "group": dictify(self.group), "resource_id": self.resource_id,
+            "resource_name": self.resource_name,
+            "resource_category": dictify(self.resource_category),
+            "public": self.public,
+            "resource_data": self.resource_data
+        }
+
+def __assign_resource_owner_role__(cursor, resource, user):
+    """Assign `user` the 'Resource Owner' role for `resource`."""
+    cursor.execute(
+        "SELECT gr.* FROM group_roles AS gr INNER JOIN roles AS r "
+        "ON gr.role_id=r.role_id WHERE r.role_name='resource-owner' "
+        "AND gr.group_id=?",
+        (str(resource.group.group_id),))
+    role = cursor.fetchone()
+    if not role:
+        cursor.execute("SELECT * FROM roles WHERE role_name='resource-owner'")
+        role = cursor.fetchone()
+        cursor.execute(
+            "INSERT INTO group_roles VALUES "
+            "(:group_role_id, :group_id, :role_id)",
+            {"group_role_id": str(uuid4()),
+             "group_id": str(resource.group.group_id),
+             "role_id": role["role_id"]})
+
+    cursor.execute(
+            "INSERT INTO group_user_roles_on_resources "
+            "VALUES ("
+            ":group_id, :user_id, :role_id, :resource_id"
+            ")",
+            {"group_id": str(resource.group.group_id),
+             "user_id": str(user.user_id),
+             "role_id": role["role_id"],
+             "resource_id": str(resource.resource_id)})
+
+@authorised_p(("group:resource:create-resource",),
+              error_description="Insufficient privileges to create a resource",
+              oauth2_scope="profile resource")
+def create_resource(
+        conn: db.DbConnection, resource_name: str,
+        resource_category: ResourceCategory, user: User,
+        public: bool) -> Resource:
+    """Create a resource item."""
+    with db.cursor(conn) as cursor:
+        group = user_group(conn, user).maybe(
+            False, lambda grp: grp)# type: ignore[misc, arg-type]
+        if not group:
+            raise MissingGroupError(
+                "User with no group cannot create a resource.")
+        resource = Resource(
+            group, uuid4(), resource_name, resource_category, public)
+        cursor.execute(
+            "INSERT INTO resources VALUES (?, ?, ?, ?, ?)",
+            (str(resource.group.group_id), str(resource.resource_id),
+             resource_name,
+             str(resource.resource_category.resource_category_id),
+             1 if resource.public else 0))
+        __assign_resource_owner_role__(cursor, resource, user)
+
+    return resource
+
+def resource_category_by_id(
+        conn: db.DbConnection, category_id: UUID) -> ResourceCategory:
+    """Retrieve a resource category by its ID."""
+    with db.cursor(conn) as cursor:
+        cursor.execute(
+            "SELECT * FROM resource_categories WHERE "
+            "resource_category_id=?",
+            (str(category_id),))
+        results = cursor.fetchone()
+        if results:
+            return ResourceCategory(
+                UUID(results["resource_category_id"]),
+                results["resource_category_key"],
+                results["resource_category_description"])
+
+    raise NotFoundError(
+        f"Could not find a ResourceCategory with ID '{category_id}'")
+
+def resource_categories(conn: db.DbConnection) -> Sequence[ResourceCategory]:
+    """Retrieve all available resource categories"""
+    with db.cursor(conn) as cursor:
+        cursor.execute("SELECT * FROM resource_categories")
+        return tuple(
+            ResourceCategory(UUID(row[0]), row[1], row[2])
+            for row in cursor.fetchall())
+    return tuple()
+
+def public_resources(conn: db.DbConnection) -> Sequence[Resource]:
+    """List all resources marked as public"""
+    categories = {
+        str(cat.resource_category_id): cat for cat in resource_categories(conn)
+    }
+    with db.cursor(conn) as cursor:
+        cursor.execute("SELECT * FROM resources WHERE public=1")
+        results = cursor.fetchall()
+        group_uuids = tuple(row[0] for row in results)
+        query = ("SELECT * FROM groups WHERE group_id IN "
+                 f"({', '.join(['?'] * len(group_uuids))})")
+        cursor.execute(query, group_uuids)
+        groups = {
+            row[0]: Group(
+                UUID(row[0]), row[1], json.loads(row[2] or "{}"))
+            for row in cursor.fetchall()
+        }
+        return tuple(
+            Resource(groups[row[0]], UUID(row[1]), row[2], categories[row[3]],
+                     bool(row[4]))
+            for row in results)
+
+def group_leader_resources(
+        conn: db.DbConnection, user: User, group: Group,
+        res_categories: Dict[UUID, ResourceCategory]) -> Sequence[Resource]:
+    """Return all the resources available to the group leader"""
+    if is_group_leader(conn, user, group):
+        with db.cursor(conn) as cursor:
+            cursor.execute("SELECT * FROM resources WHERE group_id=?",
+                           (str(group.group_id),))
+            return tuple(
+                Resource(group, UUID(row[1]), row[2],
+                         res_categories[UUID(row[3])], bool(row[4]))
+                for row in cursor.fetchall())
+    return tuple()
+
+def user_resources(conn: db.DbConnection, user: User) -> Sequence[Resource]:
+    """List the resources available to the user"""
+    categories = { # Repeated in `public_resources` function
+        cat.resource_category_id: cat for cat in resource_categories(conn)
+    }
+    with db.cursor(conn) as cursor:
+        def __all_resources__(group) -> Sequence[Resource]:
+            gl_resources = group_leader_resources(conn, user, group, categories)
+
+            cursor.execute(
+                ("SELECT resources.* FROM group_user_roles_on_resources "
+                 "LEFT JOIN resources "
+                 "ON group_user_roles_on_resources.resource_id=resources.resource_id "
+                 "WHERE group_user_roles_on_resources.group_id = ? "
+                 "AND group_user_roles_on_resources.user_id = ?"),
+                (str(group.group_id), str(user.user_id)))
+            rows = cursor.fetchall()
+            private_res = tuple(
+                Resource(group, UUID(row[1]), row[2], categories[UUID(row[3])],
+                         bool(row[4]))
+                for row in rows)
+            return tuple({
+                res.resource_id: res
+                for res in
+                (private_res + gl_resources + public_resources(conn))# type: ignore[operator]
+            }.values())
+
+        # Fix the typing here
+        return user_group(conn, user).map(__all_resources__).maybe(# type: ignore[arg-type,misc]
+            public_resources(conn), lambda res: res)# type: ignore[arg-type,return-value]
+
+def resource_data(conn, resource, offset: int = 0, limit: Optional[int] = None) -> tuple[dict, ...]:
+    """
+    Retrieve the data for `resource`, optionally limiting the number of items.
+    """
+    resource_data_function = {
+        "mrna": mrna_resource_data,
+        "genotype": genotype_resource_data,
+        "phenotype": phenotype_resource_data
+    }
+    with db.cursor(conn) as cursor:
+        return tuple(
+            dict(data_row) for data_row in
+            resource_data_function[
+                resource.resource_category.resource_category_key](
+                    cursor, resource.resource_id, offset, limit))
+
+def attach_resource_data(cursor: db.DbCursor, resource: Resource) -> Resource:
+    """Attach the linked data to the resource"""
+    resource_data_function = {
+        "mrna": mrna_resource_data,
+        "genotype": genotype_resource_data,
+        "phenotype": phenotype_resource_data
+    }
+    category = resource.resource_category
+    data_rows = tuple(
+        dict(data_row) for data_row in
+        resource_data_function[category.resource_category_key](
+            cursor, resource.resource_id))
+    return Resource(
+        resource.group, resource.resource_id, resource.resource_name,
+        resource.resource_category, resource.public, data_rows)
+
+def mrna_resource_data(cursor: db.DbCursor,
+                       resource_id: UUID,
+                       offset: int = 0,
+                       limit: Optional[int] = None) -> Sequence[sqlite3.Row]:
+    """Fetch data linked to a mRNA resource"""
+    cursor.execute(
+        (("SELECT * FROM mrna_resources AS mr "
+          "INNER JOIN linked_mrna_data AS lmr "
+          "ON mr.data_link_id=lmr.data_link_id "
+          "WHERE mr.resource_id=?") + (
+              f" LIMIT {limit} OFFSET {offset}" if bool(limit) else "")),
+        (str(resource_id),))
+    return cursor.fetchall()
+
+def genotype_resource_data(
+        cursor: db.DbCursor,
+        resource_id: UUID,
+        offset: int = 0,
+        limit: Optional[int] = None) -> Sequence[sqlite3.Row]:
+    """Fetch data linked to a Genotype resource"""
+    cursor.execute(
+        (("SELECT * FROM genotype_resources AS gr "
+          "INNER JOIN linked_genotype_data AS lgd "
+          "ON gr.data_link_id=lgd.data_link_id "
+          "WHERE gr.resource_id=?") + (
+              f" LIMIT {limit} OFFSET {offset}" if bool(limit) else "")),
+        (str(resource_id),))
+    return cursor.fetchall()
+
+def phenotype_resource_data(
+        cursor: db.DbCursor,
+        resource_id: UUID,
+        offset: int = 0,
+        limit: Optional[int] = None) -> Sequence[sqlite3.Row]:
+    """Fetch data linked to a Phenotype resource"""
+    cursor.execute(
+        ("SELECT * FROM phenotype_resources AS pr "
+         "INNER JOIN linked_phenotype_data AS lpd "
+         "ON pr.data_link_id=lpd.data_link_id "
+         "WHERE pr.resource_id=?") + (
+             f" LIMIT {limit} OFFSET {offset}" if bool(limit) else ""),
+        (str(resource_id),))
+    return cursor.fetchall()
+
+def resource_by_id(
+        conn: db.DbConnection, user: User, resource_id: UUID) -> Resource:
+    """Retrieve a resource by its ID."""
+    if not authorised_for(
+            conn, user, ("group:resource:view-resource",),
+            (resource_id,))[resource_id]:
+        raise AuthorisationError(
+            "You are not authorised to access resource with id "
+            f"'{resource_id}'.")
+
+    with db.cursor(conn) as cursor:
+        cursor.execute("SELECT * FROM resources WHERE resource_id=:id",
+                       {"id": str(resource_id)})
+        row = cursor.fetchone()
+        if row:
+            return Resource(
+                group_by_id(conn, UUID(row["group_id"])),
+                UUID(row["resource_id"]), row["resource_name"],
+                resource_category_by_id(conn, row["resource_category_id"]),
+                bool(int(row["public"])))
+
+    raise NotFoundError(f"Could not find a resource with id '{resource_id}'")
+
+def __link_mrna_data_to_resource__(
+        conn: db.DbConnection, resource: Resource, data_link_id: UUID) -> dict:
+    """Link mRNA Assay data with a resource."""
+    with db.cursor(conn) as cursor:
+        params = {
+            "group_id": str(resource.group.group_id),
+            "resource_id": str(resource.resource_id),
+            "data_link_id": str(data_link_id)
+        }
+        cursor.execute(
+            "INSERT INTO mrna_resources VALUES"
+            "(:group_id, :resource_id, :data_link_id)",
+            params)
+        return params
+
+def __link_geno_data_to_resource__(
+        conn: db.DbConnection, resource: Resource, data_link_id: UUID) -> dict:
+    """Link Genotype data with a resource."""
+    with db.cursor(conn) as cursor:
+        params = {
+            "group_id": str(resource.group.group_id),
+            "resource_id": str(resource.resource_id),
+            "data_link_id": str(data_link_id)
+        }
+        cursor.execute(
+            "INSERT INTO genotype_resources VALUES"
+            "(:group_id, :resource_id, :data_link_id)",
+            params)
+        return params
+
+def __link_pheno_data_to_resource__(
+        conn: db.DbConnection, resource: Resource, data_link_id: UUID) -> dict:
+    """Link Phenotype data with a resource."""
+    with db.cursor(conn) as cursor:
+        params = {
+            "group_id": str(resource.group.group_id),
+            "resource_id": str(resource.resource_id),
+            "data_link_id": str(data_link_id)
+        }
+        cursor.execute(
+            "INSERT INTO phenotype_resources VALUES"
+            "(:group_id, :resource_id, :data_link_id)",
+            params)
+        return params
+
+def link_data_to_resource(
+        conn: db.DbConnection, user: User, resource_id: UUID, dataset_type: str,
+        data_link_id: UUID) -> dict:
+    """Link data to resource."""
+    if not authorised_for(
+            conn, user, ("group:resource:edit-resource",),
+            (resource_id,))[resource_id]:
+        raise AuthorisationError(
+            "You are not authorised to link data to resource with id "
+            f"{resource_id}")
+
+    resource = with_db_connection(partial(
+        resource_by_id, user=user, resource_id=resource_id))
+    return {
+        "mrna": __link_mrna_data_to_resource__,
+        "genotype": __link_geno_data_to_resource__,
+        "phenotype": __link_pheno_data_to_resource__,
+    }[dataset_type.lower()](conn, resource, data_link_id)
+
+def __unlink_mrna_data_to_resource__(
+        conn: db.DbConnection, resource: Resource, data_link_id: UUID) -> dict:
+    """Unlink data from mRNA Assay resources"""
+    with db.cursor(conn) as cursor:
+        cursor.execute("DELETE FROM mrna_resources "
+                       "WHERE resource_id=? AND data_link_id=?",
+                       (str(resource.resource_id), str(data_link_id)))
+        return {
+            "resource_id": str(resource.resource_id),
+            "dataset_type": resource.resource_category.resource_category_key,
+            "data_link_id": data_link_id
+        }
+
+def __unlink_geno_data_to_resource__(
+        conn: db.DbConnection, resource: Resource, data_link_id: UUID) -> dict:
+    """Unlink data from Genotype resources"""
+    with db.cursor(conn) as cursor:
+        cursor.execute("DELETE FROM genotype_resources "
+                       "WHERE resource_id=? AND data_link_id=?",
+                       (str(resource.resource_id), str(data_link_id)))
+        return {
+            "resource_id": str(resource.resource_id),
+            "dataset_type": resource.resource_category.resource_category_key,
+            "data_link_id": data_link_id
+        }
+
+def __unlink_pheno_data_to_resource__(
+        conn: db.DbConnection, resource: Resource, data_link_id: UUID) -> dict:
+    """Unlink data from Phenotype resources"""
+    with db.cursor(conn) as cursor:
+        cursor.execute("DELETE FROM phenotype_resources "
+                       "WHERE resource_id=? AND data_link_id=?",
+                       (str(resource.resource_id), str(data_link_id)))
+        return {
+            "resource_id": str(resource.resource_id),
+            "dataset_type": resource.resource_category.resource_category_key,
+            "data_link_id": str(data_link_id)
+        }
+
+def unlink_data_from_resource(
+        conn: db.DbConnection, user: User, resource_id: UUID, data_link_id: UUID):
+    """Unlink data from resource."""
+    if not authorised_for(
+            conn, user, ("group:resource:edit-resource",),
+            (resource_id,))[resource_id]:
+        raise AuthorisationError(
+            "You are not authorised to link data to resource with id "
+            f"{resource_id}")
+
+    resource = with_db_connection(partial(
+        resource_by_id, user=user, resource_id=resource_id))
+    dataset_type = resource.resource_category.resource_category_key
+    return {
+        "mrna": __unlink_mrna_data_to_resource__,
+        "genotype": __unlink_geno_data_to_resource__,
+        "phenotype": __unlink_pheno_data_to_resource__,
+    }[dataset_type.lower()](conn, resource, data_link_id)
+
+def organise_resources_by_category(resources: Sequence[Resource]) -> dict[
+        ResourceCategory, tuple[Resource]]:
+    """Organise the `resources` by their categories."""
+    def __organise__(accumulator, resource):
+        category = resource.resource_category
+        return {
+            **accumulator,
+            category: accumulator.get(category, tuple()) + (resource,)
+        }
+    return reduce(__organise__, resources, {})
+
+def __attach_data__(
+        data_rows: Sequence[sqlite3.Row],
+        resources: Sequence[Resource]) -> Sequence[Resource]:
+    def __organise__(acc, row):
+        resource_id = UUID(row["resource_id"])
+        return {
+            **acc,
+            resource_id: acc.get(resource_id, tuple()) + (dict(row),)
+        }
+    organised: dict[UUID, tuple[dict, ...]] = reduce(__organise__, data_rows, {})
+    return tuple(
+        Resource(
+            resource.group, resource.resource_id, resource.resource_name,
+            resource.resource_category, resource.public,
+            organised.get(resource.resource_id, tuple()))
+        for resource in resources)
+
+def attach_mrna_resources_data(
+        cursor, resources: Sequence[Resource]) -> Sequence[Resource]:
+    """Attach linked data to mRNA Assay resources"""
+    placeholders = ", ".join(["?"] * len(resources))
+    cursor.execute(
+        "SELECT * FROM mrna_resources AS mr INNER JOIN linked_mrna_data AS lmd"
+        " ON mr.data_link_id=lmd.data_link_id "
+        f"WHERE mr.resource_id IN ({placeholders})",
+        tuple(str(resource.resource_id) for resource in resources))
+    return __attach_data__(cursor.fetchall(), resources)
+
+def attach_genotype_resources_data(
+        cursor, resources: Sequence[Resource]) -> Sequence[Resource]:
+    """Attach linked data to Genotype resources"""
+    placeholders = ", ".join(["?"] * len(resources))
+    cursor.execute(
+        "SELECT * FROM genotype_resources AS gr "
+        "INNER JOIN linked_genotype_data AS lgd "
+        "ON gr.data_link_id=lgd.data_link_id "
+        f"WHERE gr.resource_id IN ({placeholders})",
+        tuple(str(resource.resource_id) for resource in resources))
+    return __attach_data__(cursor.fetchall(), resources)
+
+def attach_phenotype_resources_data(
+        cursor, resources: Sequence[Resource]) -> Sequence[Resource]:
+    """Attach linked data to Phenotype resources"""
+    placeholders = ", ".join(["?"] * len(resources))
+    cursor.execute(
+        "SELECT * FROM phenotype_resources AS pr "
+        "INNER JOIN linked_phenotype_data AS lpd "
+        "ON pr.data_link_id=lpd.data_link_id "
+        f"WHERE pr.resource_id IN ({placeholders})",
+        tuple(str(resource.resource_id) for resource in resources))
+    return __attach_data__(cursor.fetchall(), resources)
+
+def attach_resources_data(
+        conn: db.DbConnection, resources: Sequence[Resource]) -> Sequence[
+            Resource]:
+    """Attach linked data for each resource in `resources`"""
+    resource_data_function = {
+        "mrna": attach_mrna_resources_data,
+        "genotype": attach_genotype_resources_data,
+        "phenotype": attach_phenotype_resources_data
+    }
+    organised = organise_resources_by_category(resources)
+    with db.cursor(conn) as cursor:
+        return tuple(
+            resource for categories in
+            (resource_data_function[category.resource_category_key](
+                cursor, rscs)
+             for category, rscs in organised.items())
+            for resource in categories)
+
+@authorised_p(
+    ("group:user:assign-role",),
+    "You cannot assign roles to users for this group.",
+    oauth2_scope="profile group role resource")
+def assign_resource_user(
+        conn: db.DbConnection, resource: Resource, user: User,
+        role: GroupRole) -> dict:
+    """Assign `role` to `user` for the specific `resource`."""
+    with db.cursor(conn) as cursor:
+        cursor.execute(
+            "INSERT INTO "
+            "group_user_roles_on_resources(group_id, user_id, role_id, "
+            "resource_id) "
+            "VALUES (?, ?, ?, ?) "
+            "ON CONFLICT (group_id, user_id, role_id, resource_id) "
+            "DO NOTHING",
+            (str(resource.group.group_id), str(user.user_id),
+             str(role.role.role_id), str(resource.resource_id)))
+        return {
+            "resource": dictify(resource),
+            "user": dictify(user),
+            "role": dictify(role),
+            "description": (
+                f"The user '{user.name}'({user.email}) was assigned the "
+                f"'{role.role.role_name}' role on resource with ID "
+                f"'{resource.resource_id}'.")}
+
+@authorised_p(
+    ("group:user:assign-role",),
+    "You cannot assign roles to users for this group.",
+    oauth2_scope="profile group role resource")
+def unassign_resource_user(
+        conn: db.DbConnection, resource: Resource, user: User,
+        role: GroupRole) -> dict:
+    """Assign `role` to `user` for the specific `resource`."""
+    with db.cursor(conn) as cursor:
+        cursor.execute(
+            "DELETE FROM group_user_roles_on_resources "
+            "WHERE group_id=? AND user_id=? AND role_id=? AND resource_id=?",
+            (str(resource.group.group_id), str(user.user_id),
+             str(role.role.role_id), str(resource.resource_id)))
+        return {
+            "resource": dictify(resource),
+            "user": dictify(user),
+            "role": dictify(role),
+            "description": (
+                f"The user '{user.name}'({user.email}) had the "
+                f"'{role.role.role_name}' role on resource with ID "
+                f"'{resource.resource_id}' taken away.")}
+
+def save_resource(
+        conn: db.DbConnection, user: User, resource: Resource) -> Resource:
+    """Update an existing resource."""
+    resource_id = resource.resource_id
+    authorised = authorised_for(
+        conn, user, ("group:resource:edit-resource",), (resource_id,))
+    if authorised[resource_id]:
+        with db.cursor(conn) as cursor:
+            cursor.execute(
+                "UPDATE resources SET "
+                "resource_name=:resource_name, "
+                "public=:public "
+                "WHERE group_id=:group_id "
+                "AND resource_id=:resource_id",
+                {
+                    "resource_name": resource.resource_name,
+                    "public": 1 if resource.public else 0,
+                    "group_id": str(resource.group.group_id),
+                    "resource_id": str(resource.resource_id)
+                })
+            return resource
+
+    raise AuthorisationError(
+        "You do not have the appropriate privileges to edit this resource.")
diff --git a/gn_auth/auth/authorisation/resources/views.py b/gn_auth/auth/authorisation/resources/views.py
new file mode 100644
index 0000000..3b2bbeb
--- /dev/null
+++ b/gn_auth/auth/authorisation/resources/views.py
@@ -0,0 +1,272 @@
+"""The views/routes for the resources package"""
+import uuid
+import json
+import sqlite3
+from functools import reduce
+
+from flask import request, jsonify, Response, Blueprint, current_app as app
+
+from gn3.auth.db_utils import with_db_connection
+
+from .checks import authorised_for
+from .models import (
+    Resource, save_resource, resource_data, resource_by_id, resource_categories,
+    assign_resource_user, link_data_to_resource, unassign_resource_user,
+    resource_category_by_id, unlink_data_from_resource,
+    create_resource as _create_resource)
+
+from ..roles import Role
+from ..errors import InvalidData, InconsistencyError, AuthorisationError
+from ..groups.models import Group, GroupRole, group_role_by_id
+
+from ... import db
+from ...dictify import dictify
+from ...authentication.oauth2.resource_server import require_oauth
+from ...authentication.users import User, user_by_id, user_by_email
+
+resources = Blueprint("resources", __name__)
+
+@resources.route("/categories", methods=["GET"])
+@require_oauth("profile group resource")
+def list_resource_categories() -> Response:
+    """Retrieve all resource categories"""
+    db_uri = app.config["AUTH_DB"]
+    with db.connection(db_uri) as conn:
+        return jsonify(tuple(
+            dictify(category) for category in resource_categories(conn)))
+
+@resources.route("/create", methods=["POST"])
+@require_oauth("profile group resource")
+def create_resource() -> Response:
+    """Create a new resource"""
+    with require_oauth.acquire("profile group resource") as the_token:
+        form = request.form
+        resource_name = form.get("resource_name")
+        resource_category_id = uuid.UUID(form.get("resource_category"))
+        db_uri = app.config["AUTH_DB"]
+        with db.connection(db_uri) as conn:
+            try:
+                resource = _create_resource(
+                    conn,
+                    resource_name,
+                    resource_category_by_id(conn, resource_category_id),
+                    the_token.user,
+                    (form.get("public") == "on"))
+                return jsonify(dictify(resource))
+            except sqlite3.IntegrityError as sql3ie:
+                if sql3ie.args[0] == ("UNIQUE constraint failed: "
+                                      "resources.resource_name"):
+                    raise InconsistencyError(
+                        "You cannot have duplicate resource names.") from sql3ie
+                app.logger.debug(
+                    f"{type(sql3ie)=}: {sql3ie=}")
+                raise
+
+@resources.route("/view/<uuid:resource_id>")
+@require_oauth("profile group resource")
+def view_resource(resource_id: uuid.UUID) -> Response:
+    """View a particular resource's details."""
+    with require_oauth.acquire("profile group resource") as the_token:
+        db_uri = app.config["AUTH_DB"]
+        with db.connection(db_uri) as conn:
+            return jsonify(dictify(resource_by_id(
+                conn, the_token.user, resource_id)))
+
+def __safe_get_requests_page__(key: str = "page") -> int:
+    """Get the results page if it exists or default to the first page."""
+    try:
+        return abs(int(request.args.get(key, "1"), base=10))
+    except ValueError as _valerr:
+        return 1
+
+def __safe_get_requests_count__(key: str = "count_per_page") -> int:
+    """Get the results page if it exists or default to the first page."""
+    try:
+        count = request.args.get(key, "0")
+        if count != 0:
+            return abs(int(count, base=10))
+        return 0
+    except ValueError as _valerr:
+        return 0
+
+@resources.route("/view/<uuid:resource_id>/data")
+@require_oauth("profile group resource")
+def view_resource_data(resource_id: uuid.UUID) -> Response:
+    """Retrieve a particular resource's data."""
+    with require_oauth.acquire("profile group resource") as the_token:
+        db_uri = app.config["AUTH_DB"]
+        count_per_page = __safe_get_requests_count__("count_per_page")
+        offset = (__safe_get_requests_page__("page") - 1)
+        with db.connection(db_uri) as conn:
+            resource = resource_by_id(conn, the_token.user, resource_id)
+            return jsonify(resource_data(
+                conn,
+                resource,
+                ((offset * count_per_page) if bool(count_per_page) else offset),
+                count_per_page))
+
+@resources.route("/data/link", methods=["POST"])
+@require_oauth("profile group resource")
+def link_data():
+    """Link group data to a specific resource."""
+    try:
+        form = request.form
+        assert "resource_id" in form, "Resource ID not provided."
+        assert "data_link_id" in form, "Data Link ID not provided."
+        assert "dataset_type" in form, "Dataset type not specified"
+        assert form["dataset_type"].lower() in (
+            "mrna", "genotype", "phenotype"), "Invalid dataset type provided."
+
+        with require_oauth.acquire("profile group resource") as the_token:
+            def __link__(conn: db.DbConnection):
+                return link_data_to_resource(
+                    conn, the_token.user, uuid.UUID(form["resource_id"]),
+                    form["dataset_type"], uuid.UUID(form["data_link_id"]))
+
+            return jsonify(with_db_connection(__link__))
+    except AssertionError as aserr:
+        raise InvalidData(aserr.args[0]) from aserr
+
+
+
+@resources.route("/data/unlink", methods=["POST"])
+@require_oauth("profile group resource")
+def unlink_data():
+    """Unlink data bound to a specific resource."""
+    try:
+        form = request.form
+        assert "resource_id" in form, "Resource ID not provided."
+        assert "data_link_id" in form, "Data Link ID not provided."
+
+        with require_oauth.acquire("profile group resource") as the_token:
+            def __unlink__(conn: db.DbConnection):
+                return unlink_data_from_resource(
+                    conn, the_token.user, uuid.UUID(form["resource_id"]),
+                    uuid.UUID(form["data_link_id"]))
+            return jsonify(with_db_connection(__unlink__))
+    except AssertionError as aserr:
+        raise InvalidData(aserr.args[0]) from aserr
+
+@resources.route("<uuid:resource_id>/user/list", methods=["GET"])
+@require_oauth("profile group resource")
+def resource_users(resource_id: uuid.UUID):
+    """Retrieve all users with access to the given resource."""
+    with require_oauth.acquire("profile group resource") as the_token:
+        def __the_users__(conn: db.DbConnection):
+            resource = resource_by_id(conn, the_token.user, resource_id)
+            authorised = authorised_for(
+                conn, the_token.user, ("group:resource:edit-resource",),
+                (resource_id,))
+            if authorised.get(resource_id, False):
+                with db.cursor(conn) as cursor:
+                    def __organise_users_n_roles__(users_n_roles, row):
+                        user_id = uuid.UUID(row["user_id"])
+                        user = users_n_roles.get(user_id, {}).get(
+                            "user", User(user_id, row["email"], row["name"]))
+                        role = GroupRole(
+                            uuid.UUID(row["group_role_id"]),
+                            resource.group,
+                            Role(uuid.UUID(row["role_id"]), row["role_name"],
+                                 bool(int(row["user_editable"])), tuple()))
+                        return {
+                            **users_n_roles,
+                            user_id: {
+                                "user": user,
+                                "user_group": Group(
+                                    uuid.UUID(row["group_id"]), row["group_name"],
+                                    json.loads(row["group_metadata"])),
+                                "roles": users_n_roles.get(
+                                    user_id, {}).get("roles", tuple()) + (role,)
+                            }
+                        }
+                    cursor.execute(
+                        "SELECT g.*, u.*, r.*, gr.group_role_id "
+                        "FROM groups AS g INNER JOIN "
+                        "group_users AS gu ON g.group_id=gu.group_id "
+                        "INNER JOIN users AS u ON gu.user_id=u.user_id "
+                        "INNER JOIN group_user_roles_on_resources AS guror "
+                        "ON u.user_id=guror.user_id INNER JOIN roles AS r "
+                        "ON guror.role_id=r.role_id "
+                        "INNER JOIN group_roles AS gr ON r.role_id=gr.role_id "
+                        "WHERE guror.resource_id=?",
+                        (str(resource_id),))
+                    return reduce(__organise_users_n_roles__, cursor.fetchall(), {})
+            raise AuthorisationError(
+                "You do not have sufficient privileges to view the resource "
+                "users.")
+        results = (
+            {
+                "user": dictify(row["user"]),
+                "user_group": dictify(row["user_group"]),
+                "roles": tuple(dictify(role) for role in row["roles"])
+            } for row in (
+                user_row for user_id, user_row
+                in with_db_connection(__the_users__).items()))
+        return jsonify(tuple(results))
+
+@resources.route("<uuid:resource_id>/user/assign", methods=["POST"])
+@require_oauth("profile group resource role")
+def assign_role_to_user(resource_id: uuid.UUID) -> Response:
+    """Assign a role on the specified resource to a user."""
+    with require_oauth.acquire("profile group resource role") as the_token:
+        try:
+            form = request.form
+            group_role_id = form.get("group_role_id", "")
+            user_email = form.get("user_email", "")
+            assert bool(group_role_id), "The role must be provided."
+            assert bool(user_email), "The user email must be provided."
+
+            def __assign__(conn: db.DbConnection) -> dict:
+                resource = resource_by_id(conn, the_token.user, resource_id)
+                user = user_by_email(conn, user_email)
+                return assign_resource_user(
+                    conn, resource, user,
+                    group_role_by_id(conn, resource.group,
+                                     uuid.UUID(group_role_id)))
+        except AssertionError as aserr:
+            raise AuthorisationError(aserr.args[0]) from aserr
+
+        return jsonify(with_db_connection(__assign__))
+
+@resources.route("<uuid:resource_id>/user/unassign", methods=["POST"])
+@require_oauth("profile group resource role")
+def unassign_role_to_user(resource_id: uuid.UUID) -> Response:
+    """Unassign a role on the specified resource from a user."""
+    with require_oauth.acquire("profile group resource role") as the_token:
+        try:
+            form = request.form
+            group_role_id = form.get("group_role_id", "")
+            user_id = form.get("user_id", "")
+            assert bool(group_role_id), "The role must be provided."
+            assert bool(user_id), "The user id must be provided."
+
+            def __assign__(conn: db.DbConnection) -> dict:
+                resource = resource_by_id(conn, the_token.user, resource_id)
+                return unassign_resource_user(
+                    conn, resource, user_by_id(conn, uuid.UUID(user_id)),
+                    group_role_by_id(conn, resource.group,
+                                     uuid.UUID(group_role_id)))
+        except AssertionError as aserr:
+            raise AuthorisationError(aserr.args[0]) from aserr
+
+        return jsonify(with_db_connection(__assign__))
+
+@resources.route("<uuid:resource_id>/toggle-public", methods=["POST"])
+@require_oauth("profile group resource role")
+def toggle_public(resource_id: uuid.UUID) -> Response:
+    """Make a resource public if it is private, or private if public."""
+    with require_oauth.acquire("profile group resource") as the_token:
+        def __toggle__(conn: db.DbConnection) -> Resource:
+            old_rsc = resource_by_id(conn, the_token.user, resource_id)
+            return save_resource(
+                conn, the_token.user, Resource(
+                    old_rsc.group, old_rsc.resource_id, old_rsc.resource_name,
+                    old_rsc.resource_category, not old_rsc.public,
+                    old_rsc.resource_data))
+
+        resource = with_db_connection(__toggle__)
+        return jsonify({
+            "resource": dictify(resource),
+            "description": (
+                "Made resource public" if resource.public
+                else "Made resource private")})
diff --git a/gn_auth/auth/authorisation/roles/__init__.py b/gn_auth/auth/authorisation/roles/__init__.py
new file mode 100644
index 0000000..293a12f
--- /dev/null
+++ b/gn_auth/auth/authorisation/roles/__init__.py
@@ -0,0 +1,3 @@
+"""Initialise the `gn3.auth.authorisation.roles` package"""
+
+from .models import Role
diff --git a/gn_auth/auth/authorisation/roles/models.py b/gn_auth/auth/authorisation/roles/models.py
new file mode 100644
index 0000000..97e11af
--- /dev/null
+++ b/gn_auth/auth/authorisation/roles/models.py
@@ -0,0 +1,161 @@
+"""Handle management of roles"""
+from uuid import UUID, uuid4
+from functools import reduce
+from typing import Any, Sequence, Iterable, NamedTuple
+
+from pymonad.either import Left, Right, Either
+
+from gn3.auth import db
+from gn3.auth.dictify import dictify
+from gn3.auth.authentication.users import User
+from gn3.auth.authorisation.errors import AuthorisationError
+
+from ..checks import authorised_p
+from ..privileges import Privilege
+from ..errors import NotFoundError
+
+class Role(NamedTuple):
+    """Class representing a role: creates immutable objects."""
+    role_id: UUID
+    role_name: str
+    user_editable: bool
+    privileges: tuple[Privilege, ...]
+
+    def dictify(self) -> dict[str, Any]:
+        """Return a dict representation of `Role` objects."""
+        return {
+            "role_id": self.role_id, "role_name": self.role_name,
+            "user_editable": self.user_editable,
+            "privileges": tuple(dictify(priv) for priv in self.privileges)
+        }
+
+def check_user_editable(role: Role):
+    """Raise an exception if `role` is not user editable."""
+    if not role.user_editable:
+        raise AuthorisationError(
+            f"The role `{role.role_name}` is not user editable.")
+
+@authorised_p(
+    privileges = ("group:role:create-role",),
+    error_description="Could not create role")
+def create_role(
+        cursor: db.DbCursor, role_name: str,
+        privileges: Iterable[Privilege]) -> Role:
+    """
+    Create a new generic role.
+
+    PARAMS:
+    * cursor: A database cursor object - This function could be used as part of
+              a transaction, hence the use of a cursor rather than a connection
+              object.
+    * role_name: The name of the role
+    * privileges: A 'list' of privileges to assign the new role
+
+    RETURNS: An immutable `gn3.auth.authorisation.roles.Role` object
+    """
+    role = Role(uuid4(), role_name, True, tuple(privileges))
+
+    cursor.execute(
+        "INSERT INTO roles(role_id, role_name, user_editable) VALUES (?, ?, ?)",
+        (str(role.role_id), role.role_name, (1 if role.user_editable else 0)))
+    cursor.executemany(
+        "INSERT INTO role_privileges(role_id, privilege_id) VALUES (?, ?)",
+        tuple((str(role.role_id), str(priv.privilege_id))
+              for priv in privileges))
+
+    return role
+
+def __organise_privileges__(roles_dict, privilege_row):
+    """Organise the privileges into their roles."""
+    role_id_str = privilege_row["role_id"]
+    if  role_id_str in roles_dict:
+        return {
+            **roles_dict,
+            role_id_str: Role(
+                UUID(role_id_str),
+                privilege_row["role_name"],
+                bool(int(privilege_row["user_editable"])),
+                roles_dict[role_id_str].privileges + (
+                    Privilege(privilege_row["privilege_id"],
+                              privilege_row["privilege_description"]),))
+        }
+
+    return {
+        **roles_dict,
+        role_id_str: Role(
+            UUID(role_id_str),
+            privilege_row["role_name"],
+            bool(int(privilege_row["user_editable"])),
+            (Privilege(privilege_row["privilege_id"],
+                       privilege_row["privilege_description"]),))
+    }
+
+def user_roles(conn: db.DbConnection, user: User) -> Sequence[Role]:
+    """Retrieve non-resource roles assigned to the user."""
+    with db.cursor(conn) as cursor:
+        cursor.execute(
+            "SELECT r.*, p.* FROM user_roles AS ur INNER JOIN roles AS r "
+            "ON ur.role_id=r.role_id INNER JOIN role_privileges AS rp "
+            "ON r.role_id=rp.role_id INNER JOIN privileges AS p "
+            "ON rp.privilege_id=p.privilege_id WHERE ur.user_id=?",
+            (str(user.user_id),))
+
+        return tuple(
+            reduce(__organise_privileges__, cursor.fetchall(), {}).values())
+    return tuple()
+
+def user_role(conn: db.DbConnection, user: User, role_id: UUID) -> Either:
+    """Retrieve a specific non-resource role assigned to the user."""
+    with db.cursor(conn) as cursor:
+        cursor.execute(
+            "SELECT r.*, p.* FROM user_roles AS ur INNER JOIN roles AS r "
+            "ON ur.role_id=r.role_id INNER JOIN role_privileges AS rp "
+            "ON r.role_id=rp.role_id INNER JOIN privileges AS p "
+            "ON rp.privilege_id=p.privilege_id "
+            "WHERE ur.user_id=? AND ur.role_id=?",
+            (str(user.user_id), str(role_id)))
+
+        results = cursor.fetchall()
+        if results:
+            return Right(tuple(
+                reduce(__organise_privileges__, results, {}).values())[0])
+        return Left(NotFoundError(
+            f"Could not find role with id '{role_id}'",))
+
+def assign_default_roles(cursor: db.DbCursor, user: User):
+    """Assign `user` some default roles."""
+    cursor.execute(
+        'SELECT role_id FROM roles WHERE role_name IN '
+        '("group-creator")')
+    role_ids = cursor.fetchall()
+    str_user_id = str(user.user_id)
+    params = tuple(
+        {"user_id": str_user_id, "role_id": row["role_id"]} for row in role_ids)
+    cursor.executemany(
+        ("INSERT INTO user_roles VALUES (:user_id, :role_id)"),
+        params)
+
+def revoke_user_role_by_name(cursor: db.DbCursor, user: User, role_name: str):
+    """Revoke a role from `user` by the role's name"""
+    cursor.execute(
+        "SELECT role_id FROM roles WHERE role_name=:role_name",
+        {"role_name": role_name})
+    role = cursor.fetchone()
+    if role:
+        cursor.execute(
+            ("DELETE FROM user_roles "
+             "WHERE user_id=:user_id AND role_id=:role_id"),
+            {"user_id": str(user.user_id), "role_id": role["role_id"]})
+
+def assign_user_role_by_name(cursor: db.DbCursor, user: User, role_name: str):
+    """Revoke a role from `user` by the role's name"""
+    cursor.execute(
+        "SELECT role_id FROM roles WHERE role_name=:role_name",
+        {"role_name": role_name})
+    role = cursor.fetchone()
+
+    if role:
+        cursor.execute(
+            ("INSERT INTO user_roles VALUES(:user_id, :role_id) "
+             "ON CONFLICT DO NOTHING"),
+            {"user_id": str(user.user_id), "role_id": role["role_id"]})
diff --git a/gn_auth/auth/authorisation/roles/views.py b/gn_auth/auth/authorisation/roles/views.py
new file mode 100644
index 0000000..3670aab
--- /dev/null
+++ b/gn_auth/auth/authorisation/roles/views.py
@@ -0,0 +1,26 @@
+"""The views/routes for the `gn3.auth.authorisation.roles` package."""
+import uuid
+
+from flask import jsonify, Response, Blueprint, current_app
+
+from gn3.auth import db
+from gn3.auth.dictify import dictify
+
+from .models import user_role
+
+from ...authentication.oauth2.resource_server import require_oauth
+
+roles = Blueprint("roles", __name__)
+
+@roles.route("/view/<uuid:role_id>", methods=["GET"])
+@require_oauth("profile role")
+def view_role(role_id: uuid.UUID) -> Response:
+    """Retrieve a user role with id `role_id`"""
+    def __error__(exc: Exception):
+        raise exc
+    with require_oauth.acquire("profile role") as the_token:
+        db_uri = current_app.config["AUTH_DB"]
+        with db.connection(db_uri) as conn:
+            the_role = user_role(conn, the_token.user, role_id)
+            return the_role.either(
+                __error__, lambda a_role: jsonify(dictify(a_role)))
diff --git a/gn_auth/auth/authorisation/users/__init__.py b/gn_auth/auth/authorisation/users/__init__.py
new file mode 100644
index 0000000..e69de29
--- /dev/null
+++ b/gn_auth/auth/authorisation/users/__init__.py
diff --git a/gn_auth/auth/authorisation/users/admin/__init__.py b/gn_auth/auth/authorisation/users/admin/__init__.py
new file mode 100644
index 0000000..8aa0743
--- /dev/null
+++ b/gn_auth/auth/authorisation/users/admin/__init__.py
@@ -0,0 +1,2 @@
+"""The admin module"""
+from .views import admin
diff --git a/gn_auth/auth/authorisation/users/admin/ui.py b/gn_auth/auth/authorisation/users/admin/ui.py
new file mode 100644
index 0000000..242c7a6
--- /dev/null
+++ b/gn_auth/auth/authorisation/users/admin/ui.py
@@ -0,0 +1,27 @@
+"""UI utilities for the auth system."""
+from functools import wraps
+from flask import flash, url_for, redirect
+
+from gn3.auth.authentication.users import User
+from gn3.auth.db_utils import with_db_connection
+from gn3.auth.authorisation.roles.models import user_roles
+
+from gn3.session import logged_in, session_user, clear_session_info
+
+def is_admin(func):
+    """Verify user is a system admin."""
+    @wraps(func)
+    @logged_in
+    def __admin__(*args, **kwargs):
+        admin_roles = [
+            role for role in with_db_connection(
+                lambda conn: user_roles(
+                    conn, User(**session_user())))
+            if role.role_name == "system-administrator"]
+        if len(admin_roles) > 0:
+            return func(*args, **kwargs)
+        flash("Expected a system administrator.", "alert-danger")
+        flash("You have been logged out of the system.", "alert-info")
+        clear_session_info()
+        return redirect(url_for("oauth2.admin.login"))
+    return __admin__
diff --git a/gn_auth/auth/authorisation/users/admin/views.py b/gn_auth/auth/authorisation/users/admin/views.py
new file mode 100644
index 0000000..c9f1887
--- /dev/null
+++ b/gn_auth/auth/authorisation/users/admin/views.py
@@ -0,0 +1,230 @@
+"""UI for admin stuff"""
+import uuid
+import json
+import random
+import string
+from functools import partial
+from datetime import datetime, timezone, timedelta
+
+from email_validator import validate_email, EmailNotValidError
+from flask import (
+    flash,
+    request,
+    url_for,
+    redirect,
+    Blueprint,
+    current_app,
+    render_template)
+
+
+from gn3 import session
+from gn3.auth import db
+from gn3.auth.db_utils import with_db_connection
+
+from gn3.auth.authentication.oauth2.models.oauth2client import (
+    save_client,
+    OAuth2Client,
+    oauth2_clients,
+    client as oauth2_client,
+    delete_client as _delete_client)
+from gn3.auth.authentication.users import (
+    User,
+    user_by_id,
+    valid_login,
+    user_by_email,
+    hash_password)
+
+from .ui import is_admin
+
+admin = Blueprint("admin", __name__)
+
+@admin.before_request
+def update_expires():
+    """Update session expiration."""
+    if session.session_info() and not session.update_expiry():
+        flash("Session has expired. Logging out...", "alert-warning")
+        session.clear_session_info()
+        return redirect(url_for("oauth2.admin.login"))
+    return None
+
+@admin.route("/dashboard", methods=["GET"])
+@is_admin
+def dashboard():
+    """Admin dashboard."""
+    return render_template("admin/dashboard.html")
+
+@admin.route("/login", methods=["GET", "POST"])
+def login():
+    """Log in to GN3 directly without OAuth2 client."""
+    if request.method == "GET":
+        return render_template(
+            "admin/login.html",
+            next_uri=request.args.get("next", "oauth2.admin.dashboard"))
+
+    form = request.form
+    next_uri = form.get("next_uri", "oauth2.admin.dashboard")
+    error_message = "Invalid email or password provided."
+    login_page = redirect(url_for("oauth2.admin.login", next=next_uri))
+    try:
+        email = validate_email(form.get("email", "").strip(),
+                               check_deliverability=False)
+        password = form.get("password")
+        with db.connection(current_app.config["AUTH_DB"]) as conn:
+            user = user_by_email(conn, email["email"])
+            if valid_login(conn, user, password):
+                session.update_session_info(
+                    user=user._asdict(),
+                    expires=(
+                        datetime.now(tz=timezone.utc) + timedelta(minutes=10)))
+                return redirect(url_for(next_uri))
+            flash(error_message, "alert-danger")
+            return login_page
+    except EmailNotValidError as _enve:
+        flash(error_message, "alert-danger")
+        return login_page
+
+@admin.route("/logout", methods=["GET"])
+def logout():
+    """Log out the admin."""
+    if not session.session_info():
+        flash("Not logged in.", "alert-info")
+        return redirect(url_for("oauth2.admin.login"))
+    session.clear_session_info()
+    flash("Logged out", "alert-success")
+    return redirect(url_for("oauth2.admin.login"))
+
+def random_string(length: int = 64) -> str:
+    """Generate a random string."""
+    return "".join(
+        random.choice(string.ascii_letters + string.digits + string.punctuation)
+        for _idx in range(0, length))
+
+def __response_types__(grant_types: tuple[str, ...]) -> tuple[str, ...]:
+    """Compute response types from grant types."""
+    resps = {
+        "password": ("token",),
+        "authorization_code": ("token", "code"),
+        "refresh_token": ("token",)
+    }
+    return tuple(set(
+        resp_typ for types_list
+        in (types for grant, types in resps.items() if grant in grant_types)
+        for resp_typ in types_list))
+
+@admin.route("/register-client", methods=["GET", "POST"])
+@is_admin
+def register_client():
+    """Register an OAuth2 client."""
+    def __list_users__(conn):
+        with db.cursor(conn) as cursor:
+            cursor.execute("SELECT * FROM users")
+            return tuple(
+                User(uuid.UUID(row["user_id"]), row["email"], row["name"])
+                for row in cursor.fetchall())
+    if request.method == "GET":
+        return render_template(
+            "admin/register-client.html",
+            scope=current_app.config["OAUTH2_SCOPE"],
+            users=with_db_connection(__list_users__),
+            current_user=session.session_user())
+
+    form = request.form
+    raw_client_secret = random_string()
+    default_redirect_uri = form["redirect_uri"]
+    grant_types = form.getlist("grants[]")
+    client = OAuth2Client(
+        client_id = uuid.uuid4(),
+        client_secret = hash_password(raw_client_secret),
+        client_id_issued_at = datetime.now(tz=timezone.utc),
+        client_secret_expires_at = datetime.fromtimestamp(0),
+        client_metadata = {
+            "client_name": "GN2 Dev Server",
+            "token_endpoint_auth_method": [
+                "client_secret_post", "client_secret_basic"],
+            "client_type": "confidential",
+            "grant_types": ["password", "authorization_code", "refresh_token"],
+            "default_redirect_uri": default_redirect_uri,
+            "redirect_uris": [default_redirect_uri] + form.get("other_redirect_uri", "").split(),
+            "response_type": __response_types__(tuple(grant_types)),
+            "scope": form.getlist("scope[]")
+        },
+        user = with_db_connection(partial(
+            user_by_id, user_id=uuid.UUID(form["user"])))
+    )
+    client = with_db_connection(partial(save_client, the_client=client))
+    return render_template(
+        "admin/registered-client.html",
+        client=client,
+        client_secret = raw_client_secret)
+
+def __parse_client__(sqlite3_row) -> dict:
+    """Parse the client details into python datatypes."""
+    return {
+        **dict(sqlite3_row),
+        "client_metadata": json.loads(sqlite3_row["client_metadata"])
+    }
+
+@admin.route("/list-client", methods=["GET"])
+@is_admin
+def list_clients():
+    """List all registered OAuth2 clients."""
+    return render_template(
+        "admin/list-oauth2-clients.html",
+        clients=with_db_connection(oauth2_clients))
+
+@admin.route("/view-client/<uuid:client_id>", methods=["GET"])
+@is_admin
+def view_client(client_id: uuid.UUID):
+    """View details of OAuth2 client with given `client_id`."""
+    return render_template(
+        "admin/view-oauth2-client.html",
+        client=with_db_connection(partial(oauth2_client, client_id=client_id)),
+        scope=current_app.config["OAUTH2_SCOPE"])
+
+@admin.route("/edit-client", methods=["POST"])
+@is_admin
+def edit_client():
+    """Edit the details of the given client."""
+    form = request.form
+    the_client = with_db_connection(partial(
+        oauth2_client, client_id=uuid.UUID(form["client_id"])))
+    if the_client.is_nothing():
+        flash("No such client.", "alert-danger")
+        return redirect(url_for("oauth2.admin.list_clients"))
+    the_client = the_client.value
+    client_metadata = {
+        **the_client.client_metadata,
+        "default_redirect_uri": form["default_redirect_uri"],
+        "redirect_uris": list(set(
+            [form["default_redirect_uri"]] +
+            form["other_redirect_uris"].split("\r\n"))),
+        "grants": form.getlist("grants[]"),
+        "scope": form.getlist("scope[]")
+    }
+    with_db_connection(partial(save_client, the_client=OAuth2Client(
+        the_client.client_id,
+        the_client.client_secret,
+        the_client.client_id_issued_at,
+        the_client.client_secret_expires_at,
+        client_metadata,
+        the_client.user)))
+    flash("Client updated.", "alert-success")
+    return redirect(url_for("oauth2.admin.view_client",
+                            client_id=the_client.client_id))
+
+@admin.route("/delete-client", methods=["POST"])
+@is_admin
+def delete_client():
+    """Delete the details of the client."""
+    form = request.form
+    the_client = with_db_connection(partial(
+        oauth2_client, client_id=uuid.UUID(form["client_id"])))
+    if the_client.is_nothing():
+        flash("No such client.", "alert-danger")
+        return redirect(url_for("oauth2.admin.list_clients"))
+    the_client = the_client.value
+    with_db_connection(partial(_delete_client, client=the_client))
+    flash((f"Client '{the_client.client_metadata.client_name}' was deleted "
+           "successfully."),
+          "alert-success")
+    return redirect(url_for("oauth2.admin.list_clients"))
diff --git a/gn_auth/auth/authorisation/users/collections/__init__.py b/gn_auth/auth/authorisation/users/collections/__init__.py
new file mode 100644
index 0000000..88ab040
--- /dev/null
+++ b/gn_auth/auth/authorisation/users/collections/__init__.py
@@ -0,0 +1 @@
+"""Package dealing with user collections."""
diff --git a/gn_auth/auth/authorisation/users/collections/models.py b/gn_auth/auth/authorisation/users/collections/models.py
new file mode 100644
index 0000000..7577fa8
--- /dev/null
+++ b/gn_auth/auth/authorisation/users/collections/models.py
@@ -0,0 +1,269 @@
+"""Handle user collections."""
+import json
+from uuid import UUID, uuid4
+from datetime import datetime
+
+from redis import Redis
+from email_validator import validate_email, EmailNotValidError
+
+from gn3.auth.authorisation.errors import InvalidData, NotFoundError
+
+from ..models import User
+
+__OLD_REDIS_COLLECTIONS_KEY__ = "collections"
+__REDIS_COLLECTIONS_KEY__ = "collections2"
+
+class CollectionJSONEncoder(json.JSONEncoder):
+    """Serialise collection objects into JSON."""
+    def default(self, obj):# pylint: disable=[arguments-renamed]
+        if isinstance(obj, UUID):
+            return str(obj)
+        if isinstance(obj, datetime):
+            return obj.strftime("%b %d %Y %I:%M%p")
+        return json.JSONEncoder.default(self, obj)
+
+def __valid_email__(email:str) -> bool:
+    """Check for email validity."""
+    try:
+        validate_email(email, check_deliverability=True)
+    except EmailNotValidError as _enve:
+        return False
+    return True
+
+def __toggle_boolean_field__(
+        rconn: Redis, email: str, field: str):
+    """Toggle the valuen of a boolean field"""
+    mig_dict = json.loads(rconn.hget("migratable-accounts", email) or "{}")
+    if bool(mig_dict):
+        rconn.hset("migratable-accounts", email,
+                   json.dumps({**mig_dict, field: not mig_dict.get(field, True)}))
+
+def __build_email_uuid_bridge__(rconn: Redis):
+    """
+    Build a connection between new accounts and old user accounts.
+
+    The only thing that is common between the two is the email address,
+    therefore, we use that to link the two items.
+    """
+    old_accounts = {
+        account["email_address"]: {
+            "user_id": account["user_id"],
+            "collections-migrated": False,
+            "resources_migrated": False
+        } for account in (
+            acct for acct in
+            (json.loads(usr) for usr in rconn.hgetall("users").values())
+            if (bool(acct.get("email_address", False)) and
+                __valid_email__(acct["email_address"])))
+    }
+    if bool(old_accounts):
+        rconn.hset("migratable-accounts", mapping={
+            key: json.dumps(value) for key,value in old_accounts.items()
+        })
+    return old_accounts
+
+def __retrieve_old_accounts__(rconn: Redis) -> dict:
+    accounts = rconn.hgetall("migratable-accounts")
+    if accounts:
+        return {
+            key: json.loads(value) for key, value in accounts.items()
+        }
+    return __build_email_uuid_bridge__(rconn)
+
+def parse_collection(coll: dict) -> dict:
+    """Parse the collection as persisted in redis to a usable python object."""
+    created = coll.get("created", coll.get("created_timestamp"))
+    changed = coll.get("changed", coll.get("changed_timestamp"))
+    return {
+        "id": UUID(coll["id"]),
+        "name": coll["name"],
+        "created": datetime.strptime(created, "%b %d %Y %I:%M%p"),
+        "changed": datetime.strptime(changed, "%b %d %Y %I:%M%p"),
+        "num_members": int(coll["num_members"]),
+        "members": coll["members"]
+    }
+
+def dump_collection(pythoncollection: dict) -> str:
+    """Convert the collection from a python object to a json string."""
+    return json.dumps(pythoncollection, cls=CollectionJSONEncoder)
+
+def __retrieve_old_user_collections__(rconn: Redis, old_user_id: UUID) -> tuple:
+    """Retrieve any old collections relating to the user."""
+    return tuple(parse_collection(coll) for coll in
+                 json.loads(rconn.hget(
+                     __OLD_REDIS_COLLECTIONS_KEY__, str(old_user_id)) or "[]"))
+
+def user_collections(rconn: Redis, user: User) -> tuple[dict, ...]:
+    """Retrieve current user collections."""
+    collections = tuple(parse_collection(coll) for coll in json.loads(
+        rconn.hget(__REDIS_COLLECTIONS_KEY__, str(user.user_id)) or
+        "[]"))
+    old_accounts = __retrieve_old_accounts__(rconn)
+    if (user.email in old_accounts and
+        not old_accounts[user.email]["collections-migrated"]):
+        old_user_id = old_accounts[user.email]["user_id"]
+        collections = tuple({
+            coll["id"]: coll for coll in (
+                collections + __retrieve_old_user_collections__(
+                    rconn, UUID(old_user_id)))
+        }.values())
+        __toggle_boolean_field__(rconn, user.email, "collections-migrated")
+        rconn.hset(
+            __REDIS_COLLECTIONS_KEY__,
+            key=str(user.user_id),
+            value=json.dumps(collections, cls=CollectionJSONEncoder))
+    return collections
+
+def save_collections(rconn: Redis, user: User, collections: tuple[dict, ...]) -> tuple[dict, ...]:
+    """Save the `collections` to redis."""
+    rconn.hset(
+        __REDIS_COLLECTIONS_KEY__,
+        str(user.user_id),
+        json.dumps(collections, cls=CollectionJSONEncoder))
+    return collections
+
+def add_to_user_collections(rconn: Redis, user: User, collection: dict) -> dict:
+    """Add `collection` to list of user collections."""
+    ucolls = user_collections(rconn, user)
+    save_collections(rconn, user, ucolls + (collection,))
+    return collection
+
+def create_collection(rconn: Redis, user: User, name: str, traits: tuple) -> dict:
+    """Create a new collection."""
+    now = datetime.utcnow()
+    return add_to_user_collections(rconn, user, {
+        "id": uuid4(),
+        "name": name,
+        "created": now,
+        "changed": now,
+        "num_members": len(traits),
+        "members": traits
+    })
+
+def get_collection(rconn: Redis, user: User, collection_id: UUID) -> dict:
+    """Retrieve the collection with ID `collection_id`."""
+    colls = tuple(coll for coll in user_collections(rconn, user)
+                  if coll["id"] == collection_id)
+    if len(colls) == 0:
+        raise NotFoundError(
+            f"Could not find a collection with ID `{collection_id}` for user "
+            f"with ID `{user.user_id}`")
+    if len(colls) > 1:
+        err = InvalidData(
+            "More than one collection was found having the ID "
+            f"`{collection_id}` for user with ID `{user.user_id}`.")
+        err.error_code = 513
+        raise err
+    return colls[0]
+
+def __raise_if_collections_empty__(user: User, collections: tuple[dict, ...]):
+    """Raise an exception if no collections are found for `user`."""
+    if len(collections) < 1:
+        raise NotFoundError(f"No collections found for user `{user.user_id}`")
+
+def __raise_if_not_single_collection__(
+        user: User, collection_id: UUID, collections: tuple[dict, ...]):
+    """
+    Raise an exception there is zero, or more than one collection for `user`.
+    """
+    if len(collections) == 0:
+        raise NotFoundError(f"No collections found for user `{user.user_id}` "
+                            f"with ID `{collection_id}`.")
+    if len(collections) > 1:
+        err = InvalidData(
+            "More than one collection was found having the ID "
+            f"`{collection_id}` for user with ID `{user.user_id}`.")
+        err.error_code = 513
+        raise err
+
+def delete_collections(rconn: Redis,
+                       user: User,
+                       collection_ids: tuple[UUID, ...]) -> tuple[dict, ...]:
+    """
+    Delete collections with the given `collection_ids` returning the deleted
+    collections.
+    """
+    ucolls = user_collections(rconn, user)
+    save_collections(
+        rconn,
+        user,
+        tuple(coll for coll in ucolls if coll["id"] not in collection_ids))
+    return tuple(coll for coll in ucolls if coll["id"] in collection_ids)
+
+def add_traits(rconn: Redis,
+               user: User,
+               collection_id: UUID,
+               traits: tuple[str, ...]) -> dict:
+    """
+    Add `traits` to the `user` collection identified by `collection_id`.
+
+    Returns: The collection with the new traits added.
+    """
+    ucolls = user_collections(rconn, user)
+    __raise_if_collections_empty__(user, ucolls)
+
+    mod_col = tuple(coll for coll in ucolls if coll["id"] == collection_id)
+    __raise_if_not_single_collection__(user, collection_id, mod_col)
+    new_members = tuple(set(tuple(mod_col[0]["members"]) + traits))
+    new_coll = {
+        **mod_col[0],
+        "members": new_members,
+        "num_members": len(new_members)
+    }
+    save_collections(
+        rconn,
+        user,
+        (tuple(coll for coll in ucolls if coll["id"] != collection_id) +
+         (new_coll,)))
+    return new_coll
+
+def remove_traits(rconn: Redis,
+                  user: User,
+                  collection_id: UUID,
+                  traits: tuple[str, ...]) -> dict:
+    """
+    Remove `traits` from the `user` collection identified by `collection_id`.
+
+    Returns: The collection with the specified `traits` removed.
+    """
+    ucolls = user_collections(rconn, user)
+    __raise_if_collections_empty__(user, ucolls)
+
+    mod_col = tuple(coll for coll in ucolls if coll["id"] == collection_id)
+    __raise_if_not_single_collection__(user, collection_id, mod_col)
+    new_members = tuple(
+        trait for trait in mod_col[0]["members"] if trait not in traits)
+    new_coll = {
+        **mod_col[0],
+        "members": new_members,
+        "num_members": len(new_members)
+    }
+    save_collections(
+        rconn,
+        user,
+        (tuple(coll for coll in ucolls if coll["id"] != collection_id) +
+         (new_coll,)))
+    return new_coll
+
+def change_name(rconn: Redis,
+                user: User,
+                collection_id: UUID,
+                new_name: str) -> dict:
+    """
+    Change the collection's name.
+
+    Returns: The collection with the new name.
+    """
+    ucolls = user_collections(rconn, user)
+    __raise_if_collections_empty__(user, ucolls)
+
+    mod_col = tuple(coll for coll in ucolls if coll["id"] == collection_id)
+    __raise_if_not_single_collection__(user, collection_id, mod_col)
+
+    new_coll = {**mod_col[0], "name": new_name}
+    save_collections(
+        rconn,
+        user,
+        (tuple(coll for coll in ucolls if coll["id"] != collection_id) +
+         (new_coll,)))
+    return new_coll
diff --git a/gn_auth/auth/authorisation/users/collections/views.py b/gn_auth/auth/authorisation/users/collections/views.py
new file mode 100644
index 0000000..1fa25a3
--- /dev/null
+++ b/gn_auth/auth/authorisation/users/collections/views.py
@@ -0,0 +1,239 @@
+"""Views regarding user collections."""
+from uuid import UUID
+
+from redis import Redis
+from flask import jsonify, request, Response, Blueprint, current_app
+
+from gn3.auth import db
+from gn3.auth.db_utils import with_db_connection
+from gn3.auth.authorisation.checks import require_json
+from gn3.auth.authorisation.errors import NotFoundError
+
+from gn3.auth.authentication.users import User, user_by_id
+from gn3.auth.authentication.oauth2.resource_server import require_oauth
+
+from .models import (
+    add_traits,
+    change_name,
+    remove_traits,
+    get_collection,
+    user_collections,
+    save_collections,
+    create_collection,
+    delete_collections as _delete_collections)
+
+collections = Blueprint("collections", __name__)
+
+@collections.route("/list")
+@require_oauth("profile user")
+def list_user_collections() -> Response:
+    """Retrieve the user ids"""
+    with (require_oauth.acquire("profile user") as the_token,
+          Redis.from_url(current_app.config["REDIS_URI"],
+                         decode_responses=True) as redisconn):
+        return jsonify(user_collections(redisconn, the_token.user))
+
+@collections.route("/<uuid:anon_id>/list")
+def list_anonymous_collections(anon_id: UUID) -> Response:
+    """Fetch anonymous collections"""
+    with Redis.from_url(
+            current_app.config["REDIS_URI"], decode_responses=True) as redisconn:
+        def __list__(conn: db.DbConnection) -> tuple:
+            try:
+                _user = user_by_id(conn, anon_id)
+                current_app.logger.warning(
+                    "Fetch collections for authenticated user using the "
+                    "`list_user_collections()` endpoint.")
+                return tuple()
+            except NotFoundError as _nfe:
+                return user_collections(
+                    redisconn, User(anon_id, "anon@ymous.user", "Anonymous User"))
+
+        return jsonify(with_db_connection(__list__))
+
+@require_oauth("profile user")
+def __new_collection_as_authenticated_user__(redisconn, name, traits):
+    """Create a new collection as an authenticated user."""
+    with require_oauth.acquire("profile user") as token:
+        return create_collection(redisconn, token.user, name, traits)
+
+def __new_collection_as_anonymous_user__(redisconn, name, traits):
+    """Create a new collection as an anonymous user."""
+    return create_collection(redisconn,
+                             User(UUID(request.json.get("anon_id")),
+                                  "anon@ymous.user",
+                                  "Anonymous User"),
+                             name,
+                             traits)
+
+@collections.route("/new", methods=["POST"])
+@require_json
+def new_user_collection() -> Response:
+    """Create a new collection."""
+    with (Redis.from_url(current_app.config["REDIS_URI"],
+                         decode_responses=True) as redisconn):
+        traits = tuple(request.json.get("traits", tuple()))# type: ignore[union-attr]
+        name = request.json.get("name")# type: ignore[union-attr]
+        if bool(request.headers.get("Authorization")):
+            return jsonify(__new_collection_as_authenticated_user__(
+                redisconn, name, traits))
+        return jsonify(__new_collection_as_anonymous_user__(
+            redisconn, name, traits))
+
+@collections.route("/<uuid:collection_id>/view", methods=["POST"])
+@require_json
+def view_collection(collection_id: UUID) -> Response:
+    """View a particular collection"""
+    with (Redis.from_url(current_app.config["REDIS_URI"],
+                         decode_responses=True) as redisconn):
+        if bool(request.headers.get("Authorization")):
+            with require_oauth.acquire("profile user") as token:
+                return jsonify(get_collection(redisconn,
+                                              token.user,
+                                              collection_id))
+        return jsonify(get_collection(
+            redisconn,
+            User(
+                UUID(request.json.get("anon_id")),#type: ignore[union-attr]
+                "anon@ymous.user",
+                "Anonymous User"),
+            collection_id))
+
+@collections.route("/anonymous/import", methods=["POST"])
+@require_json
+@require_oauth("profile user")
+def import_anonymous() -> Response:
+    """Import anonymous collections."""
+    with (require_oauth.acquire("profile user") as token,
+          Redis.from_url(current_app.config["REDIS_URI"],
+                         decode_responses=True) as redisconn):
+        anon_id = UUID(request.json.get("anon_id"))#type: ignore[union-attr]
+        anon_colls = user_collections(redisconn, User(
+            anon_id, "anon@ymous.user", "Anonymous User"))
+        save_collections(
+            redisconn,
+            token.user,
+            (user_collections(redisconn, token.user) +
+             anon_colls))
+        redisconn.hdel("collections", str(anon_id))
+        return jsonify({
+            "message": f"Import of {len(anon_colls)} was successful."
+        })
+
+@collections.route("/anonymous/delete", methods=["POST"])
+@require_json
+@require_oauth("profile user")
+def delete_anonymous() -> Response:
+    """Delete anonymous collections."""
+    with (require_oauth.acquire("profile user") as _token,
+          Redis.from_url(current_app.config["REDIS_URI"],
+                         decode_responses=True) as redisconn):
+        anon_id = UUID(request.json.get("anon_id"))#type: ignore[union-attr]
+        anon_colls = user_collections(redisconn, User(
+            anon_id, "anon@ymous.user", "Anonymous User"))
+        redisconn.hdel("collections", str(anon_id))
+        return jsonify({
+            "message": f"Deletion of {len(anon_colls)} was successful."
+        })
+
+@collections.route("/delete", methods=["POST"])
+@require_json
+def delete_collections():
+    """Delete specified collections."""
+    with (Redis.from_url(current_app.config["REDIS_URI"],
+                         decode_responses=True) as redisconn):
+        coll_ids = tuple(UUID(cid) for cid in request.json["collection_ids"])
+        deleted = _delete_collections(
+            redisconn,
+            User(request.json["anon_id"], "anon@ymous.user", "Anonymous User"),
+            coll_ids)
+        if bool(request.headers.get("Authorization")):
+            with require_oauth.acquire("profile user") as token:
+                deleted = deleted + _delete_collections(
+                    redisconn, token.user, coll_ids)
+
+        return jsonify({
+            "message": f"Deleted {len(deleted)} collections."})
+
+@collections.route("/<uuid:collection_id>/traits/remove", methods=["POST"])
+@require_json
+def remove_traits_from_collection(collection_id: UUID) -> Response:
+    """Remove specified traits from collection with ID `collection_id`."""
+    if len(request.json["traits"]) < 1:#type: ignore[index]
+        return jsonify({"message": "No trait to remove from collection."})
+
+    the_traits = tuple(request.json["traits"])#type: ignore[index]
+    with (Redis.from_url(current_app.config["REDIS_URI"],
+                         decode_responses=True) as redisconn):
+        if not bool(request.headers.get("Authorization")):
+            coll = remove_traits(
+                redisconn,
+                User(request.json["anon_id"],#type: ignore[index]
+                     "anon@ymous.user",
+                     "Anonymous User"),
+                collection_id,
+                the_traits)
+        else:
+            with require_oauth.acquire("profile user") as token:
+                coll = remove_traits(
+                    redisconn, token.user, collection_id, the_traits)
+
+        return jsonify({
+            "message": f"Deleted {len(the_traits)} traits from collection.",
+            "collection": coll
+        })
+
+@collections.route("/<uuid:collection_id>/traits/add", methods=["POST"])
+@require_json
+def add_traits_to_collection(collection_id: UUID) -> Response:
+    """Add specified traits to collection with ID `collection_id`."""
+    if len(request.json["traits"]) < 1:#type: ignore[index]
+        return jsonify({"message": "No trait to add to collection."})
+
+    the_traits = tuple(request.json["traits"])#type: ignore[index]
+    with (Redis.from_url(current_app.config["REDIS_URI"],
+                         decode_responses=True) as redisconn):
+        if not bool(request.headers.get("Authorization")):
+            coll = add_traits(
+                redisconn,
+                User(request.json["anon_id"],#type: ignore[index]
+                     "anon@ymous.user",
+                     "Anonymous User"),
+                collection_id,
+                the_traits)
+        else:
+            with require_oauth.acquire("profile user") as token:
+                coll = add_traits(
+                    redisconn, token.user, collection_id, the_traits)
+
+        return jsonify({
+            "message": f"Added {len(the_traits)} traits to collection.",
+            "collection": coll
+        })
+
+@collections.route("/<uuid:collection_id>/rename", methods=["POST"])
+@require_json
+def rename_collection(collection_id: UUID) -> Response:
+    """Rename the given collection"""
+    if not bool(request.json["new_name"]):#type: ignore[index]
+        return jsonify({"message": "No new name to change to."})
+
+    new_name = request.json["new_name"]#type: ignore[index]
+    with (Redis.from_url(current_app.config["REDIS_URI"],
+                         decode_responses=True) as redisconn):
+        if not bool(request.headers.get("Authorization")):
+            coll = change_name(redisconn,
+                               User(UUID(request.json["anon_id"]),#type: ignore[index]
+                                    "anon@ymous.user",
+                                    "Anonymous User"),
+                               collection_id,
+                               new_name)
+        else:
+            with require_oauth.acquire("profile user") as token:
+                coll = change_name(
+                    redisconn, token.user, collection_id, new_name)
+
+        return jsonify({
+            "message": "Collection rename successful.",
+            "collection": coll
+        })
diff --git a/gn_auth/auth/authorisation/users/masquerade/__init__.py b/gn_auth/auth/authorisation/users/masquerade/__init__.py
new file mode 100644
index 0000000..69d64f0
--- /dev/null
+++ b/gn_auth/auth/authorisation/users/masquerade/__init__.py
@@ -0,0 +1 @@
+"""Package to deal with masquerading."""
diff --git a/gn_auth/auth/authorisation/users/masquerade/models.py b/gn_auth/auth/authorisation/users/masquerade/models.py
new file mode 100644
index 0000000..9f24b6b
--- /dev/null
+++ b/gn_auth/auth/authorisation/users/masquerade/models.py
@@ -0,0 +1,67 @@
+"""Functions for handling masquerade."""
+from uuid import uuid4
+from functools import wraps
+from datetime import datetime
+
+from flask import current_app as app
+
+from gn3.auth import db
+
+from gn3.auth.authorisation.errors import ForbiddenAccess
+from gn3.auth.authorisation.roles.models import user_roles
+
+from gn3.auth.authentication.users import User
+from gn3.auth.authentication.oauth2.models.oauth2token import (
+    OAuth2Token, save_token)
+
+__FIVE_HOURS__ = (60 * 60 * 5)
+
+def can_masquerade(func):
+    """Security decorator."""
+    @wraps(func)
+    def __checker__(*args, **kwargs):
+        if len(args) == 3:
+            conn, token, _masq_user = args
+        elif len(args) == 2:
+            conn, token = args
+        elif len(args) == 1:
+            conn = args[0]
+            token = kwargs["original_token"]
+        else:
+            conn = kwargs["conn"]
+            token = kwargs["original_token"]
+
+        masq_privs = [priv for role in user_roles(conn, token.user)
+                      for priv in role.privileges
+                      if priv.privilege_id == "system:user:masquerade"]
+        if len(masq_privs) == 0:
+            raise ForbiddenAccess(
+                "You do not have the ability to masquerade as another user.")
+        return func(*args, **kwargs)
+    return __checker__
+
+@can_masquerade
+def masquerade_as(
+        conn: db.DbConnection,
+        original_token: OAuth2Token,
+        masqueradee: User) -> OAuth2Token:
+    """Get a token that enables `masquerader` to act as `masqueradee`."""
+    token_details = app.config["OAUTH2_SERVER"].generate_token(
+        client=original_token.client,
+        grant_type="authorization_code",
+        user=masqueradee,
+        expires_in=__FIVE_HOURS__,
+        include_refresh_token=True)
+    new_token = OAuth2Token(
+        token_id=uuid4(),
+        client=original_token.client,
+        token_type=token_details["token_type"],
+        access_token=token_details["access_token"],
+        refresh_token=token_details.get("refresh_token"),
+        scope=original_token.scope,
+        revoked=False,
+        issued_at=datetime.now(),
+        expires_in=token_details["expires_in"],
+        user=masqueradee)
+    save_token(conn, new_token)
+    return new_token
diff --git a/gn_auth/auth/authorisation/users/masquerade/views.py b/gn_auth/auth/authorisation/users/masquerade/views.py
new file mode 100644
index 0000000..43286a1
--- /dev/null
+++ b/gn_auth/auth/authorisation/users/masquerade/views.py
@@ -0,0 +1,48 @@
+"""Endpoints for user masquerade"""
+from uuid import UUID
+from functools import partial
+
+from flask import request, jsonify, Response, Blueprint
+
+from gn3.auth.db_utils import with_db_connection
+from gn3.auth.authorisation.errors import InvalidData
+from gn3.auth.authorisation.checks import require_json
+
+from gn3.auth.authentication.users import user_by_id
+from gn3.auth.authentication.oauth2.resource_server import require_oauth
+
+from .models import masquerade_as
+
+masq = Blueprint("masquerade", __name__)
+
+@masq.route("/", methods=["POST"])
+@require_oauth("profile user masquerade")
+@require_json
+def masquerade() -> Response:
+    """Masquerade as a particular user."""
+    with require_oauth.acquire("profile user masquerade") as token:
+        masqueradee_id = UUID(request.json["masquerade_as"])#type: ignore[index]
+        if masqueradee_id == token.user.user_id:
+            raise InvalidData("You are not allowed to masquerade as yourself.")
+
+        masq_user = with_db_connection(partial(
+            user_by_id, user_id=masqueradee_id))
+        def __masq__(conn):
+            new_token = masquerade_as(conn, original_token=token, masqueradee=masq_user)
+            return new_token
+        def __dump_token__(tok):
+            return {
+                key: value for key, value in (tok._asdict().items())
+                if key in ("access_token", "refresh_token", "expires_in",
+                           "token_type")
+            }
+        return jsonify({
+            "original": {
+                "user": token.user._asdict(),
+                "token": __dump_token__(token)
+            },
+            "masquerade_as": {
+                "user": masq_user._asdict(),
+                "token": __dump_token__(with_db_connection(__masq__))
+            }
+        })
diff --git a/gn_auth/auth/authorisation/users/models.py b/gn_auth/auth/authorisation/users/models.py
new file mode 100644
index 0000000..89c1d22
--- /dev/null
+++ b/gn_auth/auth/authorisation/users/models.py
@@ -0,0 +1,66 @@
+"""Functions for acting on users."""
+import uuid
+from functools import reduce
+
+from gn3.auth import db
+from gn3.auth.authorisation.roles.models import Role
+from gn3.auth.authorisation.checks import authorised_p
+from gn3.auth.authorisation.privileges import Privilege
+
+from gn3.auth.authentication.users import User
+
+@authorised_p(
+    ("system:user:list",),
+    "You do not have the appropriate privileges to list users.",
+    oauth2_scope="profile user")
+def list_users(conn: db.DbConnection) -> tuple[User, ...]:
+    """List out all users."""
+    with db.cursor(conn) as cursor:
+        cursor.execute("SELECT * FROM users")
+        return tuple(
+            User(uuid.UUID(row["user_id"]), row["email"], row["name"])
+            for row in cursor.fetchall())
+
+def __build_resource_roles__(rows):
+    def __build_roles__(roles, row):
+        role_id = uuid.UUID(row["role_id"])
+        priv = Privilege(row["privilege_id"], row["privilege_description"])
+        role = roles.get(role_id, Role(
+            role_id, row["role_name"], bool(row["user_editable"]), tuple()))
+        return {
+            **roles,
+            role_id: Role(role_id, role.role_name, role.user_editable, role.privileges + (priv,))
+        }
+    def __build__(acc, row):
+        resource_id = uuid.UUID(row["resource_id"])
+        return {
+            **acc,
+            resource_id: __build_roles__(acc.get(resource_id, {}), row)
+        }
+    return {
+        resource_id: tuple(roles.values())
+        for resource_id, roles in reduce(__build__, rows, {}).items()
+    }
+
+# @authorised_p(
+#     ("",),
+#     ("You do not have the appropriate privileges to view a user's roles on "
+#      "resources."))
+def user_resource_roles(conn: db.DbConnection, user: User) -> dict[uuid.UUID, tuple[Role, ...]]:
+    """Fetch all the user's roles on resources."""
+    with db.cursor(conn) as cursor:
+        cursor.execute(
+            "SELECT res.*, rls.*, p.*"
+            "FROM resources AS res INNER JOIN "
+            "group_user_roles_on_resources AS guror "
+            "ON res.resource_id=guror.resource_id "
+            "LEFT JOIN roles AS rls "
+            "ON guror.role_id=rls.role_id "
+            "LEFT JOIN role_privileges AS rp "
+            "ON rls.role_id=rp.role_id "
+            "LEFT JOIN privileges AS p "
+            "ON rp.privilege_id=p.privilege_id "
+            "WHERE guror.user_id = ?",
+            (str(user.user_id),))
+        return __build_resource_roles__(
+            (dict(row) for row in cursor.fetchall()))
diff --git a/gn_auth/auth/authorisation/users/views.py b/gn_auth/auth/authorisation/users/views.py
new file mode 100644
index 0000000..826e222
--- /dev/null
+++ b/gn_auth/auth/authorisation/users/views.py
@@ -0,0 +1,176 @@
+"""User authorisation endpoints."""
+import traceback
+from typing import Any
+from functools import partial
+
+import sqlite3
+from email_validator import validate_email, EmailNotValidError
+from flask import request, jsonify, Response, Blueprint, current_app
+
+from gn3.auth import db
+from gn3.auth.dictify import dictify
+from gn3.auth.db_utils import with_db_connection
+
+from .models import list_users
+from .masquerade.views import masq
+from .collections.views import collections
+
+from ..groups.models import user_group as _user_group
+from ..resources.models import user_resources as _user_resources
+from ..roles.models import assign_default_roles, user_roles as _user_roles
+from ..errors import (
+    NotFoundError, UsernameError, PasswordError, UserRegistrationError)
+
+from ...authentication.oauth2.resource_server import require_oauth
+from ...authentication.users import User, save_user, set_user_password
+from ...authentication.oauth2.models.oauth2token import token_by_access_token
+
+users = Blueprint("users", __name__)
+users.register_blueprint(masq, url_prefix="/masquerade")
+users.register_blueprint(collections, url_prefix="/collections")
+
+@users.route("/", methods=["GET"])
+@require_oauth("profile")
+def user_details() -> Response:
+    """Return user's details."""
+    with require_oauth.acquire("profile") as the_token:
+        user = the_token.user
+        user_dets = {
+            "user_id": user.user_id, "email": user.email, "name": user.name,
+            "group": False
+        }
+        with db.connection(current_app.config["AUTH_DB"]) as conn:
+            the_group = _user_group(conn, user).maybe(# type: ignore[misc]
+                False, lambda grp: grp)# type: ignore[arg-type]
+            return jsonify({
+                **user_dets,
+                "group": dictify(the_group) if the_group else False
+            })
+
+@users.route("/roles", methods=["GET"])
+@require_oauth("role")
+def user_roles() -> Response:
+    """Return the non-resource roles assigned to the user."""
+    with require_oauth.acquire("role") as token:
+        with db.connection(current_app.config["AUTH_DB"]) as conn:
+            return jsonify(tuple(
+                dictify(role) for role in _user_roles(conn, token.user)))
+
+def validate_password(password, confirm_password) -> str:
+    """Validate the provided password."""
+    if len(password) < 8:
+        raise PasswordError("The password must be at least 8 characters long.")
+
+    if password != confirm_password:
+        raise PasswordError("Mismatched password values")
+
+    return password
+
+def validate_username(name: str) -> str:
+    """Validate the provides name."""
+    if name == "":
+        raise UsernameError("User's name not provided.")
+
+    return name
+
+def __assert_not_logged_in__(conn: db.DbConnection):
+    bearer = request.headers.get('Authorization')
+    if bearer:
+        token = token_by_access_token(conn, bearer.split(None)[1]).maybe(# type: ignore[misc]
+            False, lambda tok: tok)
+        if token:
+            raise UserRegistrationError(
+                "Cannot register user while authenticated")
+
+@users.route("/register", methods=["POST"])
+def register_user() -> Response:
+    """Register a user."""
+    with db.connection(current_app.config["AUTH_DB"]) as conn:
+        __assert_not_logged_in__(conn)
+
+        try:
+            form = request.form
+            email = validate_email(form.get("email", "").strip(),
+                                   check_deliverability=True)
+            password = validate_password(
+                form.get("password", "").strip(),
+                form.get("confirm_password", "").strip())
+            user_name = validate_username(form.get("user_name", "").strip())
+            with db.cursor(conn) as cursor:
+                user, _hashed_password = set_user_password(
+                    cursor, save_user(
+                        cursor, email["email"], user_name), password)
+                assign_default_roles(cursor, user)
+                return jsonify(
+                    {
+                        "user_id": user.user_id,
+                        "email": user.email,
+                        "name": user.name
+                    })
+        except sqlite3.IntegrityError as sq3ie:
+            current_app.logger.debug(traceback.format_exc())
+            raise UserRegistrationError(
+                "A user with that email already exists") from sq3ie
+        except EmailNotValidError as enve:
+            current_app.logger.debug(traceback.format_exc())
+            raise(UserRegistrationError(f"Email Error: {str(enve)}")) from enve
+
+    raise Exception(
+        "unknown_error", "The system experienced an unexpected error.")
+
+@users.route("/group", methods=["GET"])
+@require_oauth("profile group")
+def user_group() -> Response:
+    """Retrieve the group in which the user is a member."""
+    with require_oauth.acquire("profile group") as the_token:
+        db_uri = current_app.config["AUTH_DB"]
+        with db.connection(db_uri) as conn:
+            group = _user_group(conn, the_token.user).maybe(# type: ignore[misc]
+                False, lambda grp: grp)# type: ignore[arg-type]
+
+        if group:
+            return jsonify(dictify(group))
+        raise NotFoundError("User is not a member of any group.")
+
+@users.route("/resources", methods=["GET"])
+@require_oauth("profile resource")
+def user_resources() -> Response:
+    """Retrieve the resources a user has access to."""
+    with require_oauth.acquire("profile resource") as the_token:
+        db_uri = current_app.config["AUTH_DB"]
+        with db.connection(db_uri) as conn:
+            return jsonify([
+                dictify(resource) for resource in
+                _user_resources(conn, the_token.user)])
+
+@users.route("group/join-request", methods=["GET"])
+@require_oauth("profile group")
+def user_join_request_exists():
+    """Check whether a user has an active group join request."""
+    def __request_exists__(conn: db.DbConnection, user: User) -> dict[str, Any]:
+        with db.cursor(conn) as cursor:
+            cursor.execute(
+                "SELECT * FROM group_join_requests WHERE requester_id=? AND "
+                "status = 'PENDING'",
+                (str(user.user_id),))
+            res = cursor.fetchone()
+            if res:
+                return {
+                    "request_id": res["request_id"],
+                    "exists": True
+                }
+        return{
+            "status": "Not found",
+            "exists": False
+        }
+    with require_oauth.acquire("profile group") as the_token:
+        return jsonify(with_db_connection(partial(
+            __request_exists__, user=the_token.user)))
+
+@users.route("/list", methods=["GET"])
+@require_oauth("profile user")
+def list_all_users() -> Response:
+    """List all the users."""
+    with require_oauth.acquire("profile group") as _the_token:
+        return jsonify(tuple(
+            dictify(user) for user in with_db_connection(list_users)))
diff --git a/gn_auth/auth/db.py b/gn_auth/auth/db.py
new file mode 100644
index 0000000..2ba6619
--- /dev/null
+++ b/gn_auth/auth/db.py
@@ -0,0 +1,78 @@
+"""Handle connection to auth database."""
+import sqlite3
+import logging
+import contextlib
+from typing import Any, Callable, Iterator, Protocol
+
+import traceback
+
+class DbConnection(Protocol):
+    """Type annotation for a generic database connection object."""
+    def cursor(self) -> Any:
+        """A cursor object"""
+        ...
+
+    def commit(self) -> Any:
+        """Commit the transaction."""
+        ...
+
+    def rollback(self) -> Any:
+        """Rollback the transaction."""
+        ...
+
+class DbCursor(Protocol):
+    """Type annotation for a generic database cursor object."""
+    def execute(self, *args, **kwargs) -> Any:
+        """Execute a single query"""
+        ...
+
+    def executemany(self, *args, **kwargs) -> Any:
+        """
+        Execute parameterized SQL statement sql against all parameter sequences
+        or mappings found in the sequence parameters.
+        """
+        ...
+
+    def fetchone(self, *args, **kwargs):
+        """Fetch single result if present, or `None`."""
+        ...
+
+    def fetchmany(self, *args, **kwargs):
+        """Fetch many results if present or `None`."""
+        ...
+
+    def fetchall(self, *args, **kwargs):
+        """Fetch all results if present or `None`."""
+        ...
+
+@contextlib.contextmanager
+def connection(db_path: str, row_factory: Callable = sqlite3.Row) -> Iterator[DbConnection]:
+    """Create the connection to the auth database."""
+    logging.debug("SQLite3 DB Path: '%s'.", db_path)
+    conn = sqlite3.connect(db_path)
+    conn.row_factory = row_factory
+    conn.set_trace_callback(logging.debug)
+    conn.execute("PRAGMA foreign_keys = ON")
+    try:
+        yield conn
+    except sqlite3.Error as exc:
+        conn.rollback()
+        logging.debug(traceback.format_exc())
+        raise exc
+    finally:
+        conn.commit()
+        conn.close()
+
+@contextlib.contextmanager
+def cursor(conn: DbConnection) -> Iterator[DbCursor]:
+    """Get a cursor from the given connection to the auth database."""
+    cur = conn.cursor()
+    try:
+        yield cur
+    except sqlite3.Error as exc:
+        conn.rollback()
+        logging.debug(traceback.format_exc())
+        raise exc
+    finally:
+        conn.commit()
+        cur.close()
diff --git a/gn_auth/auth/db_utils.py b/gn_auth/auth/db_utils.py
new file mode 100644
index 0000000..c06b026
--- /dev/null
+++ b/gn_auth/auth/db_utils.py
@@ -0,0 +1,14 @@
+"""Some common auth db utilities"""
+from typing import Any, Callable
+from flask import current_app
+
+from . import db
+
+def with_db_connection(func: Callable[[db.DbConnection], Any]) -> Any:
+    """
+    Takes a function of one argument `func`, whose one argument is a database
+    connection.
+    """
+    db_uri = current_app.config["AUTH_DB"]
+    with db.connection(db_uri) as conn:
+        return func(conn)
diff --git a/gn_auth/auth/dictify.py b/gn_auth/auth/dictify.py
new file mode 100644
index 0000000..f9337f6
--- /dev/null
+++ b/gn_auth/auth/dictify.py
@@ -0,0 +1,12 @@
+"""Module for dictifying objects"""
+
+from typing import Any, Protocol
+
+class Dictifiable(Protocol):# pylint: disable=[too-few-public-methods]
+    """Type annotation for generic object with a `dictify` method."""
+    def dictify(self):
+        """Convert the object to a dict"""
+
+def dictify(obj: Dictifiable) -> dict[str, Any]:
+    """Turn `obj` to a dict representation."""
+    return obj.dictify()
diff --git a/gn_auth/auth/views.py b/gn_auth/auth/views.py
new file mode 100644
index 0000000..56eace7
--- /dev/null
+++ b/gn_auth/auth/views.py
@@ -0,0 +1,21 @@
+"""The Auth(oris|entic)ation routes/views"""
+from flask import Blueprint
+
+from .authentication.oauth2.views import auth
+
+from .authorisation.data.views import data
+from .authorisation.users.views import users
+from .authorisation.users.admin import admin
+from .authorisation.roles.views import roles
+from .authorisation.groups.views import groups
+from .authorisation.resources.views import resources
+
+oauth2 = Blueprint("oauth2", __name__)
+
+oauth2.register_blueprint(auth, url_prefix="/")
+oauth2.register_blueprint(data, url_prefix="/data")
+oauth2.register_blueprint(users, url_prefix="/user")
+oauth2.register_blueprint(roles, url_prefix="/role")
+oauth2.register_blueprint(admin, url_prefix="/admin")
+oauth2.register_blueprint(groups, url_prefix="/group")
+oauth2.register_blueprint(resources, url_prefix="/resource")