diff --git a/pyproject.toml b/pyproject.toml
index 035d03facc..ad359256d7 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -63,6 +63,7 @@ module = [
     "django_auth_ldap.*",
     "django_cte.*",
     "django_otp.*",
+    "django_scim.*",
     "django_sendfile.*",
     "django_statsd.*",
     "DNS.*",
@@ -84,6 +85,7 @@ module = [
     "pyuca.*",
     "re2.*",
     "requests_oauthlib.*",
+    "scim2_filter_parser.attr_paths",
     "scrapy.*",
     "social_core.*",
     "social_django.*",
diff --git a/requirements/common.in b/requirements/common.in
index 87242166e9..138d733476 100644
--- a/requirements/common.in
+++ b/requirements/common.in
@@ -189,3 +189,6 @@ google-re2
 
 # For querying recursive group membership
 django-cte
+
+# SCIM integration
+django-scim2
diff --git a/requirements/dev.txt b/requirements/dev.txt
index 59cd28f087..1040057dac 100644
--- a/requirements/dev.txt
+++ b/requirements/dev.txt
@@ -377,8 +377,10 @@ django[argon2]==3.2.7 \
     #   django-formtools
     #   django-otp
     #   django-phonenumber-field
+    #   django-scim2
     #   django-sendfile2
     #   django-two-factor-auth
+    #   scim2-filter-parser
 django-auth-ldap==3.0.0 \
     --hash=sha256:19ee19034f344d9efd07ed88d3187e256ec33ae39d6a47222083b89f7d35c5f6 \
     --hash=sha256:1f2d5c562d9ba9a5e9a64099ae9798e1a63840a11afe4d1c4a9c74121f066eaa
@@ -406,6 +408,9 @@ django-phonenumber-field==5.2.0 \
     --hash=sha256:52b2e5970133ec5ab701218b802f7ab237229854dc95fd239b7e9e77dc43731d \
     --hash=sha256:5547fb2b2cc690a306ba77a5038419afc8fa8298a486fb7895008e9067cc7e75
     # via django-two-factor-auth
+django-scim2==0.17.0 \
+    --hash=sha256:dc3cb3c0d5b6ebf4ae8a28dd1dac1e0658fb543c8c178e72e3c19975816da092
+    # via -r requirements/common.in
 django-sendfile2==0.6.0 \
     --hash=sha256:7f850040ddc29c9c42192ed85b915465a3ed7cced916c4fafdd5eda057dd06ec
     # via -r requirements/common.in
@@ -1344,6 +1349,7 @@ python-dateutil==2.8.2 \
     # via
     #   -r requirements/common.in
     #   botocore
+    #   django-scim2
     #   moto
 python-debian==0.1.40 \
     --hash=sha256:385dfb965eca75164d256486c7cf9bae772d24144249fd18b9d15d3cffb70eea \
@@ -1558,6 +1564,9 @@ s3transfer==0.5.0 \
     --hash=sha256:50ed823e1dc5868ad40c8dc92072f757aa0e653a192845c94a3b676f4a62da4c \
     --hash=sha256:9c1dc369814391a6bda20ebbf4b70a0f34630592c9aa520856bf384916af2803
     # via boto3
+scim2-filter-parser==0.3.5 \
+    --hash=sha256:f46b6ffa01cdad6011d3d991bd167af1a9822ab917c225bdf49bc7a44ad4ae53
+    # via django-scim2
 https://github.com/scrapy/scrapy/archive/c5b1ee810167266fcd259f263dbfc0fe0204761a.zip#egg=Scrapy==2.5.0+git \
     --hash=sha256:d12f88f2cfb31e487170ee4e68f6e59a2af100ee690add873831c368fac6e0a7
     # via -r requirements/dev.in
@@ -1599,6 +1608,9 @@ six==1.16.0 \
     #   talon-core
     #   traitlets
     #   w3lib
+sly==0.3 \
+    --hash=sha256:be6a3825b042a9e1b6f5730fc747e6d983c917f0f002d798d0b9f86ca5c05ad9
+    # via scim2-filter-parser
 snakeviz==2.1.0 \
     --hash=sha256:8ce375b18ae4a749516d7e6c6fbbf8be6177c53974f53534d8eadb646cd279b1 \
     --hash=sha256:92ad876fb6a201a7e23a6b85ea96d9643a51e285667c253a8653643804f7cb68
diff --git a/requirements/prod.txt b/requirements/prod.txt
index 69faa3663e..c655d8d5d8 100644
--- a/requirements/prod.txt
+++ b/requirements/prod.txt
@@ -231,8 +231,10 @@ django[argon2]==3.2.7 \
     #   django-formtools
     #   django-otp
     #   django-phonenumber-field
+    #   django-scim2
     #   django-sendfile2
     #   django-two-factor-auth
+    #   scim2-filter-parser
 django-auth-ldap==3.0.0 \
     --hash=sha256:19ee19034f344d9efd07ed88d3187e256ec33ae39d6a47222083b89f7d35c5f6 \
     --hash=sha256:1f2d5c562d9ba9a5e9a64099ae9798e1a63840a11afe4d1c4a9c74121f066eaa
@@ -260,6 +262,9 @@ django-phonenumber-field==5.2.0 \
     --hash=sha256:52b2e5970133ec5ab701218b802f7ab237229854dc95fd239b7e9e77dc43731d \
     --hash=sha256:5547fb2b2cc690a306ba77a5038419afc8fa8298a486fb7895008e9067cc7e75
     # via django-two-factor-auth
+django-scim2==0.17.0 \
+    --hash=sha256:dc3cb3c0d5b6ebf4ae8a28dd1dac1e0658fb543c8c178e72e3c19975816da092
+    # via -r requirements/common.in
 django-sendfile2==0.6.0 \
     --hash=sha256:7f850040ddc29c9c42192ed85b915465a3ed7cced916c4fafdd5eda057dd06ec
     # via -r requirements/common.in
@@ -909,6 +914,7 @@ python-dateutil==2.8.2 \
     # via
     #   -r requirements/common.in
     #   botocore
+    #   django-scim2
 python-gcm==0.4 \
     --hash=sha256:511c35fc5ae829f7fc3cbdb45c4ec3fda02f85e4fae039864efe82682ccb9c18
     # via -r requirements/common.in
@@ -1059,6 +1065,9 @@ s3transfer==0.5.0 \
     --hash=sha256:50ed823e1dc5868ad40c8dc92072f757aa0e653a192845c94a3b676f4a62da4c \
     --hash=sha256:9c1dc369814391a6bda20ebbf4b70a0f34630592c9aa520856bf384916af2803
     # via boto3
+scim2-filter-parser==0.3.5 \
+    --hash=sha256:f46b6ffa01cdad6011d3d991bd167af1a9822ab917c225bdf49bc7a44ad4ae53
+    # via django-scim2
 sentry-sdk==1.3.1 \
     --hash=sha256:ebe99144fa9618d4b0e7617e7929b75acd905d258c3c779edcd34c0adfffe26c \
     --hash=sha256:f33d34c886d0ba24c75ea8885a8b3a172358853c7cbde05979fc99c29ef7bc52
@@ -1081,6 +1090,9 @@ six==1.16.0 \
     #   qrcode
     #   talon-core
     #   traitlets
+sly==0.3 \
+    --hash=sha256:be6a3825b042a9e1b6f5730fc747e6d983c917f0f002d798d0b9f86ca5c05ad9
+    # via scim2-filter-parser
 social-auth-app-django==5.0.0 \
     --hash=sha256:52241a25445a010ab1c108bafff21fc5522d5c8cd0d48a92c39c7371824b065d \
     --hash=sha256:b6e3132ce087cdd6e1707aeb1b588be41d318408fcf6395435da0bc6fe9a9795
diff --git a/version.py b/version.py
index b12b083d62..1cb2d4da1a 100644
--- a/version.py
+++ b/version.py
@@ -48,4 +48,4 @@ API_FEATURE_LEVEL = 105
 #   historical commits sharing the same major version, in which case a
 #   minor version bump suffices.
 
-PROVISION_VERSION = "162.2"
+PROVISION_VERSION = "162.3"
diff --git a/zerver/lib/export.py b/zerver/lib/export.py
index 7e12baf987..6e77317397 100644
--- a/zerver/lib/export.py
+++ b/zerver/lib/export.py
@@ -150,6 +150,7 @@ ALL_ZULIP_TABLES = {
     "zerver_scheduledemail_users",
     "zerver_scheduledmessage",
     "zerver_scheduledmessagenotificationemail",
+    "zerver_scimclient",
     "zerver_service",
     "zerver_stream",
     "zerver_submessage",
@@ -199,6 +200,8 @@ NON_EXPORTED_TABLES = {
     "zerver_scheduledemail",
     "zerver_scheduledemail_users",
     "zerver_scheduledmessage",
+    # SCIMClient should be manually created for the new realm after importing.
+    "zerver_scimclient",
     # These tables are related to a user's 2FA authentication
     # configuration, which will need to be set up again on the new
     # server.
diff --git a/zerver/lib/scim.py b/zerver/lib/scim.py
new file mode 100644
index 0000000000..50e7cf5637
--- /dev/null
+++ b/zerver/lib/scim.py
@@ -0,0 +1,363 @@
+from typing import Any, Callable, Dict, List, Optional, Type, Union
+
+import django_scim.constants as scim_constants
+import django_scim.exceptions as scim_exceptions
+from django.conf import settings
+from django.core.exceptions import ValidationError
+from django.db import models, transaction
+from django.http import HttpRequest
+from django_scim.adapters import SCIMUser
+from scim2_filter_parser.attr_paths import AttrPath
+
+from zerver.lib.actions import (
+    check_change_full_name,
+    do_change_user_delivery_email,
+    do_create_user,
+    do_deactivate_user,
+    do_reactivate_user,
+)
+from zerver.lib.email_validation import email_allowed_for_realm, validate_email_not_already_in_realm
+from zerver.lib.request import RequestNotes
+from zerver.lib.subdomains import get_subdomain
+from zerver.models import (
+    DisposableEmailError,
+    DomainNotAllowedForRealmError,
+    EmailContainsPlusError,
+    UserProfile,
+)
+
+
+class ZulipSCIMUser(SCIMUser):
+    """With django-scim2, the core of a project's SCIM implementation is
+    this user adapter class, which defines how to translate between the
+    concepts of users in the SCIM specification and the Zulip users.
+    """
+
+    id_field = "id"
+
+    def __init__(self, obj: UserProfile, request: Optional[HttpRequest] = None) -> None:
+        # We keep the function signature from the superclass, but this actually
+        # shouldn't be called with request being None.
+        assert request is not None
+
+        # self.obj is populated appropriately by django-scim2 views with
+        # an instance of UserProfile - either fetched from the database
+        # or constructed via UserProfile() if the request currently being
+        # handled is a User creation request (POST).
+        self.obj: UserProfile
+
+        super().__init__(obj, request)
+        self.subdomain = get_subdomain(request)
+        self.config = settings.SCIM_CONFIG[self.subdomain]
+
+        # These attributes are custom to this class and will be
+        # populated with values in handle_replace and similar methods
+        # in response to a request for the the corresponding
+        # UserProfile fields to change. The .save() method inspects
+        # these fields an executes the requested changes.
+        self._email_new_value: Optional[str] = None
+        self._is_active_new_value: Optional[bool] = None
+        self._full_name_new_value: Optional[str] = None
+        self._password_set_to: Optional[str] = None
+
+    def is_new_user(self) -> bool:
+        return not bool(self.obj.id)
+
+    @property
+    def display_name(self) -> str:
+        """
+        Return the displayName of the user per the SCIM spec.
+
+        Overridden because UserProfile uses the .full_name attribute,
+        while the superclass expects .first_name and .last_name.
+        """
+        return self.obj.full_name
+
+    def to_dict(self) -> Dict[str, Any]:
+        """
+        Return a ``dict`` conforming to the SCIM User Schema,
+        ready for conversion to a JSON object.
+
+        The attribute names appearing in the dict are those defined in the SCIM User Schema:
+        https://datatracker.ietf.org/doc/html/rfc7643#section-4.1
+        """
+        if self.config["name_formatted_included"]:
+            name = {
+                "formatted": self.obj.full_name,
+            }
+        else:
+            # Some clients (e.g. Okta) operate with a first_name,
+            # last_name model and don't support a full name field.
+            # While we strive never to do this in the project because
+            # not every culture has the first/last name structure,
+            # Okta's design means we have to convert our full_name
+            # into a first_name/last_name pair to provide to the
+            # client.  We do naive conversion with `split`.
+            if " " in self.obj.full_name:
+                first_name, last_name = self.obj.full_name.split(" ", 1)
+            else:
+                first_name, last_name = self.obj.full_name, ""
+            name = {
+                "givenName": first_name,
+                "familyName": last_name,
+            }
+        d = dict(
+            {
+                "schemas": [scim_constants.SchemaURI.USER],
+                "id": self.obj.id,
+                "userName": self.obj.delivery_email,
+                "name": name,
+                "displayName": self.display_name,
+                "active": self.obj.is_active,
+                # meta is a property implemented in the superclass
+                # TODO: The upstream implementation uses `user_profile.date_joined`
+                # as the value of the lastModified meta attribute, which is not
+                # a correct simplification. We should add proper tracking
+                # of this value.
+                "meta": self.meta,
+            }
+        )
+
+        return d
+
+    def from_dict(self, d: Dict[str, Any]) -> None:
+        """Consume a dictionary conforming to the SCIM User Schema. The
+        dictionary was originally submitted as JSON by the client in
+        PUT (update a user) and POST (create a new user) requests.  A
+        PUT request tells us to update User attributes to match those
+        passed in the dict.  A POST request tells us to create a new
+        User with attributes as specified in the dict.
+
+        The superclass implements some very basic default behavior,
+        that doesn't support changing attributes via our actions.py
+        functions (which update audit logs, send events, etc.) or
+        doing application-specific validation.
+
+        Thus, we've completely overriden the upstream implementation
+        to store the values of the supported attributes that the
+        request would like to change. Actually modifying the database
+        is implemented in self.save().
+
+        Given that SCIMUser is an adapter class, this method is meant
+        to be completely overridden, and we can expect it remain the
+        case that no important django-scim2 logic relies on the
+        superclass's implementation of this function.
+        """
+        email = d.get("userName")
+        assert isinstance(email, str)
+        self.change_delivery_email(email)
+
+        name_attr_dict = d.get("name", {})
+        if self.config["name_formatted_included"]:
+            full_name = name_attr_dict.get("formatted", "")
+        else:
+            # Some providers (e.g. Okta) don't provide name.formatted.
+            first_name = name_attr_dict.get("givenName", "")
+            last_name = name_attr_dict.get("familyName", "")
+            full_name = f"{first_name} {last_name}".strip()
+
+        if full_name:
+            assert isinstance(full_name, str)
+            self.change_full_name(full_name)
+
+        if self.is_new_user() and not full_name:
+            raise scim_exceptions.BadRequestError(
+                "Must specify name.formatted, name.givenName or name.familyName when creating a new user"
+            )
+
+        active = d.get("active")
+        if self.is_new_user() and not active:
+            raise scim_exceptions.BadRequestError("New user must have active=True")
+
+        if active is not None:
+            assert isinstance(active, bool)
+            self.change_is_active(active)
+
+    def change_delivery_email(self, new_value: str) -> None:
+        # Note that the email_allowed_for_realm check that usually
+        # appears adjacent to validate_email is present in save().
+        self.validate_email(new_value)
+        if self.obj.delivery_email != new_value:
+            self._email_new_value = new_value
+
+    def change_full_name(self, new_value: str) -> None:
+        if new_value and self.obj.full_name != new_value:
+            self._full_name_new_value = new_value
+
+    def change_is_active(self, new_value: bool) -> None:
+        if new_value is not None and new_value != self.obj.is_active:
+            self._is_active_new_value = new_value
+
+    def handle_replace(
+        self,
+        path: Optional[AttrPath],
+        value: Union[str, List[object], Dict[AttrPath, object]],
+        operation: Any,
+    ) -> None:
+        """
+        PATCH requests specify a list of operations of types "add", "remove", "replace".
+        So far we only implement "replace" as that should be sufficient.
+
+        This method is forked from the superclass and is called to handle "replace"
+        PATCH operations. Such an operation tells us to change the values
+        of a User's attributes as specified. The superclass implements a very basic
+        behavior in this method and is meant to be overriden, since this is an adapter class.
+        """
+        if not isinstance(value, dict):
+            # Restructure for use in loop below. Taken from the
+            # overriden upstream method.
+            assert path is not None
+            value = {path: value}
+
+        assert isinstance(value, dict)
+        for path, val in (value or {}).items():
+            if path.first_path == ("userName", None, None):
+                assert isinstance(val, str)
+                self.change_delivery_email(val)
+            elif path.first_path == ("name", "formatted", None):
+                # TODO: Add support name_formatted_included=False config like we do
+                # for updates via PUT.
+                assert isinstance(val, str)
+                self.change_full_name(val)
+            elif path.first_path == ("active", None, None):
+                assert isinstance(val, bool)
+                self.change_is_active(val)
+            else:
+                raise scim_exceptions.NotImplementedError("Not Implemented")
+
+        self.save()
+
+    def save(self) -> None:
+        """
+        This method is called at the end of operations modifying a user,
+        and is responsible for actually applying the requested changes,
+        writing them to the database.
+        """
+        realm = RequestNotes.get_notes(self._request).realm
+        assert realm is not None
+
+        email_new_value = getattr(self, "_email_new_value", None)
+        is_active_new_value = getattr(self, "_is_active_new_value", None)
+        full_name_new_value = getattr(self, "_full_name_new_value", None)
+        password = getattr(self, "_password_set_to", None)
+
+        # Clean up the internal "pending change" state, now that we've
+        # fetched the values:
+        self._email_new_value = None
+        self._is_active_new_value = None
+        self._full_name_new_value = None
+        self._password_set_to = None
+
+        if email_new_value:
+            try:
+                # Note that the validate_email check that usually
+                # appears adjacent to email_allowed_for_realm is
+                # present in save().
+                email_allowed_for_realm(email_new_value, realm)
+            except DomainNotAllowedForRealmError:
+                raise scim_exceptions.BadRequestError(
+                    "This email domain isn't allowed in this organization."
+                )
+            except DisposableEmailError:  # nocoverage
+                raise scim_exceptions.BadRequestError(
+                    "Disposable email domains are not allowed for this realm."
+                )
+            except EmailContainsPlusError:  # nocoverage
+                raise scim_exceptions.BadRequestError("Email address can't contain + characters.")
+
+            try:
+                validate_email_not_already_in_realm(realm, email_new_value)
+            except ValidationError as e:
+                raise ConflictError("Email address already in use: " + str(e))
+
+        if self.is_new_user():
+            self.obj = do_create_user(
+                email_new_value,
+                password,
+                realm,
+                full_name_new_value,
+                acting_user=None,
+            )
+            return
+
+        with transaction.atomic():
+            # We process full_name first here, since it's the only one that can fail.
+            if full_name_new_value:
+                check_change_full_name(self.obj, full_name_new_value, acting_user=None)
+
+            if email_new_value:
+                do_change_user_delivery_email(self.obj, email_new_value)
+
+            if is_active_new_value is not None and is_active_new_value:
+                do_reactivate_user(self.obj, acting_user=None)
+            elif is_active_new_value is not None and not is_active_new_value:
+                do_deactivate_user(self.obj, acting_user=None)
+
+    def delete(self) -> None:
+        """
+        This is consistent with Okta SCIM - users don't get DELETEd, they're deactivated
+        by changing their "active" attr to False.
+        """
+        raise scim_exceptions.BadRequestError(
+            'DELETE operation not supported. Use PUT or PATCH to modify the "active" attribute instead.'
+        )
+
+
+def get_extra_model_filter_kwargs_getter(
+    model: Type[models.Model],
+) -> Callable[[HttpRequest, Any, Any], Dict[str, object]]:
+    """Registered as GET_EXTRA_MODEL_FILTER_KWARGS_GETTER in our
+    SCIM configuration.
+
+    Returns a function which generates additional kwargs
+    to add to QuerySet's .filter() when fetching a UserProfile
+    corresponding to the requested SCIM User from the database.
+
+    It's *crucial* for security that we filter by realm_id (based on
+    the subdomain of the request) to prevent a SCIM client authorized
+    for subdomain X from being able to interact with all of the Users
+    on the entire server.
+
+    This should be extended for Groups when implementing them by
+    checking the `model` parameter; because we only support
+    UserProfiles, such a check is unnecessary.
+    """
+
+    def get_extra_filter_kwargs(
+        request: HttpRequest, *args: Any, **kwargs: Any
+    ) -> Dict[str, object]:
+        realm = RequestNotes.get_notes(request).realm
+        assert realm is not None
+        return {"realm_id": realm.id, "is_bot": False}
+
+    return get_extra_filter_kwargs
+
+
+def base_scim_location_getter(request: HttpRequest, *args: Any, **kwargs: Any) -> str:
+    """Used as the base url for constructing the Location of a SCIM resource.
+
+    Since SCIM synchronization is scoped to an individual realm, we
+    need these locations to be namespaced within the realm's domain
+    namespace, which is conveniently accessed via realm.uri.
+    """
+
+    realm = RequestNotes.get_notes(request).realm
+    assert realm is not None
+
+    return realm.uri
+
+
+class ConflictError(scim_exceptions.IntegrityError):
+    """
+    Per https://datatracker.ietf.org/doc/html/rfc7644#section-3.3
+
+    If the service provider determines that the creation of the requested
+    resource conflicts with existing resources (e.g., a "User" resource
+    with a duplicate "userName"), the service provider MUST return HTTP
+    status code 409 (Conflict) with a "scimType" error code of
+    "uniqueness"
+
+    scim_exceptions.IntegrityError class omits to include the scimType.
+    """
+
+    scim_type = "uniqueness"
diff --git a/zerver/lib/scim_filter.py b/zerver/lib/scim_filter.py
new file mode 100644
index 0000000000..a3dff20388
--- /dev/null
+++ b/zerver/lib/scim_filter.py
@@ -0,0 +1,62 @@
+from typing import List, Optional, Tuple
+
+from django.http import HttpRequest
+from django_scim.filters import UserFilterQuery
+
+from zerver.lib.request import RequestNotes
+
+
+# This is in a separate file due to circular import issues django-scim2 runs into
+# when this is placed in zerver.lib.scim.
+class ZulipUserFilterQuery(UserFilterQuery):
+    """This class implements the filter functionality of SCIM2.
+    E.g. requests such as
+    /scim/v2/Users?filter=userName eq "hamlet@zulip.com"
+    can be made to refer to resources via their properties.
+    This gets fairly complicated in its full scope
+    (https://datatracker.ietf.org/doc/html/rfc7644#section-3.4.2.2)
+    and django-scim2 implements an entire mechanism of converting
+    this SCIM2 filter syntax into SQL queries.
+
+    What we have to do in this class is to customize django-scim2 so
+    that it knows which SCIM attributes map to which UserProfile
+    fields.  We can assume that get_extra_model_filter_kwargs_getter
+    has already ensured that we will only interact with non-bot user
+    accounts in the realm associated with this SCIM configuration.
+    """
+
+    # attr_map describes which table.column the given SCIM2 User
+    # attributes refer to.
+    attr_map = {
+        # attr, sub attr, uri
+        ("userName", None, None): "zerver_userprofile.delivery_email",
+        # We can only reasonably support filtering by name.formatted
+        # as UserProfile.full_name is its equivalent. We don't store
+        # first/last name information for UserProfile, so we can't
+        # support filtering based on name.givenName or name.familyName.
+        ("name", "formatted", None): "zerver_userprofile.full_name",
+        ("active", None, None): "zerver_userprofile.is_active",
+    }
+
+    # joins tells django-scim2 to always add the specified JOINS
+    # to the formed SQL queries. We need to JOIN the Realm table
+    # because we need to limit the results to the realm (subdomain)
+    # of the request.
+    joins = ("INNER JOIN zerver_realm ON zerver_realm.id = realm_id",)
+
+    @classmethod
+    def get_extras(cls, q: str, request: Optional[HttpRequest] = None) -> Tuple[str, List[object]]:
+        """
+        Return extra SQL and params to be attached to end of current Query's
+        SQL and params. The return format matches the format that should be used
+        for providing raw SQL with params to Django's .raw():
+        https://docs.djangoproject.com/en/3.2/topics/db/sql/#passing-parameters-into-raw
+
+        Here we ensure that results are limited to the subdomain of the request
+        and also exclude bots, as we currently don't want them to be managed by SCIM2.
+        """
+        assert request is not None
+        realm = RequestNotes.get_notes(request).realm
+        assert realm is not None
+
+        return "AND zerver_realm.id = %s AND zerver_userprofile.is_bot = False", [realm.id]
diff --git a/zerver/lib/test_classes.py b/zerver/lib/test_classes.py
index ae485282c5..083bebc97e 100644
--- a/zerver/lib/test_classes.py
+++ b/zerver/lib/test_classes.py
@@ -326,6 +326,12 @@ Output:
         self.validate_api_response_openapi(url, "patch", result, info, kwargs)
         return result
 
+    def json_patch(self, url: str, payload: Dict[str, Any] = {}, **kwargs: Any) -> HttpResponse:
+        data = orjson.dumps(payload)
+        django_client = self.client  # see WRAPPER_COMMENT
+        self.set_http_headers(kwargs)
+        return django_client.patch(url, data=data, content_type="application/json", **kwargs)
+
     @instrument_url
     def client_put(self, url: str, info: Dict[str, Any] = {}, **kwargs: Any) -> HttpResponse:
         encoded = urllib.parse.urlencode(info)
@@ -333,6 +339,12 @@ Output:
         self.set_http_headers(kwargs)
         return django_client.put(url, encoded, **kwargs)
 
+    def json_put(self, url: str, payload: Dict[str, Any] = {}, **kwargs: Any) -> HttpResponse:
+        data = orjson.dumps(payload)
+        django_client = self.client  # see WRAPPER_COMMENT
+        self.set_http_headers(kwargs)
+        return django_client.put(url, data=data, content_type="application/json", **kwargs)
+
     @instrument_url
     def client_delete(self, url: str, info: Dict[str, Any] = {}, **kwargs: Any) -> HttpResponse:
         encoded = urllib.parse.urlencode(info)
diff --git a/zerver/lib/test_helpers.py b/zerver/lib/test_helpers.py
index 711cacf674..81fa75f397 100644
--- a/zerver/lib/test_helpers.py
+++ b/zerver/lib/test_helpers.py
@@ -489,6 +489,12 @@ def write_instrumentation_reports(full_suite: bool, include_webhooks: bool) -> N
             "static/(?P<path>.+)",
             "flush_caches",
             "external_content/(?P<digest>[^/]+)/(?P<received_url>[^/]+)",
+            # These are SCIM2 urls overriden from django-scim2 to return Not Implemented.
+            # We actually test them, but it's not being detected as a tested pattern,
+            # possibly due to the use of re_path. TODO: Investigate and get them
+            # recognized as tested.
+            "scim/v2/Groups(?:/(?P<uuid>[^/]+))?",
+            "scim/v2/Groups/.search",
             *(webhook.url for webhook in WEBHOOK_INTEGRATIONS if not include_webhooks),
         }
 
diff --git a/zerver/management/commands/add_scim_client.py b/zerver/management/commands/add_scim_client.py
new file mode 100644
index 0000000000..c2c1bddadf
--- /dev/null
+++ b/zerver/management/commands/add_scim_client.py
@@ -0,0 +1,20 @@
+from argparse import ArgumentParser
+from typing import Any
+
+from zerver.lib.management import ZulipBaseCommand
+from zerver.models import SCIMClient
+
+
+class Command(ZulipBaseCommand):
+    help = """Create a SCIM client entry in the database."""
+
+    def add_arguments(self, parser: ArgumentParser) -> None:
+        self.add_realm_args(parser)
+        parser.add_argument("name", help="name of the client")
+
+    def handle(self, *args: Any, **options: Any) -> None:
+        client_name = options["name"]
+        realm = self.get_realm(options)
+        assert realm
+
+        SCIMClient.objects.create(realm=realm, name=client_name)
diff --git a/zerver/middleware.py b/zerver/middleware.py
index 037e311a84..00952aa845 100644
--- a/zerver/middleware.py
+++ b/zerver/middleware.py
@@ -28,6 +28,8 @@ from django.utils.cache import patch_vary_headers
 from django.utils.deprecation import MiddlewareMixin
 from django.utils.translation import gettext as _
 from django.views.csrf import csrf_failure as html_csrf_failure
+from django_scim.middleware import SCIMAuthCheckMiddleware
+from django_scim.settings import scim_settings
 from sentry_sdk import capture_exception
 from sentry_sdk.integrations.logging import ignore_logger
 
@@ -44,7 +46,7 @@ from zerver.lib.subdomains import get_subdomain
 from zerver.lib.types import ViewFuncT
 from zerver.lib.user_agent import parse_user_agent
 from zerver.lib.utils import statsd
-from zerver.models import Realm, flush_per_request_caches, get_realm
+from zerver.models import Realm, SCIMClient, flush_per_request_caches, get_realm
 
 logger = logging.getLogger("zulip.requests")
 slow_query_logger = logging.getLogger("zulip.slow_queries")
@@ -664,3 +666,71 @@ class ZulipCommonMiddleware(CommonMiddleware):
         if settings.RUNNING_INSIDE_TORNADO:
             return False
         return super().should_redirect_with_slash(request)
+
+
+def validate_scim_bearer_token(request: HttpRequest) -> Optional[SCIMClient]:
+    """
+    This function verifies the request is allowed to make SCIM requests on this subdomain,
+    by checking the provided bearer token and ensuring it matches a scim client configured
+    for this subdomain in settings.SCIM_CONFIG.
+    If succesful, returns the corresponding SCIMClient object. Returns None otherwise.
+    """
+
+    subdomain = get_subdomain(request)
+    scim_config_dict = settings.SCIM_CONFIG.get(subdomain)
+    if not scim_config_dict:
+        return None
+
+    valid_bearer_token = scim_config_dict.get("bearer_token")
+    scim_client_name = scim_config_dict.get("scim_client_name")
+    # We really don't want a misconfiguration where this is unset,
+    # allowing free access to the SCIM API:
+    assert valid_bearer_token
+    assert scim_client_name
+
+    if request.headers.get("Authorization") != f"Bearer {valid_bearer_token}":
+        return None
+
+    request_notes = RequestNotes.get_notes(request)
+    assert request_notes.realm
+
+    # While API authentication code paths are sufficiently high
+    # traffic that we prefer to use a cache, SCIM is much lower
+    # traffic, and doing a database query is plenty fast.
+    return SCIMClient.objects.get(realm=request_notes.realm, name=scim_client_name)
+
+
+class ZulipSCIMAuthCheckMiddleware(SCIMAuthCheckMiddleware):
+    """
+    Overriden version of middleware implemented in django-scim2
+    (https://github.com/15five/django-scim2/blob/master/src/django_scim/middleware.py)
+    to also handle authenticating the client.
+    """
+
+    def process_request(self, request: HttpRequest) -> Optional[HttpResponse]:
+        # This determines whether this is a SCIM request based on the request's path
+        # and if it is, logs request information, including the body, as well as the response
+        # for debugging purposes to the `django_scim.middleware` logger, at DEBUG level.
+        # We keep those logs in /var/log/zulip/scim.log
+        if self.should_log_request(request):
+            self.log_request(request)
+
+        # Here we verify the request is indeed to a SCIM endpoint. That's ensured
+        # by comparing the path with self.reverse_url, which is the root SCIM path /scim/b2/.
+        # Of course we don't want to proceed with authenticating the request for SCIM
+        # if a non-SCIM endpoint is being queried.
+        if not request.path.startswith(self.reverse_url):
+            return None
+
+        scim_client = validate_scim_bearer_token(request)
+        if not scim_client:
+            response = HttpResponse(status=401)
+            response["WWW-Authenticate"] = scim_settings.WWW_AUTHENTICATE_HEADER
+            return response
+
+        # The client has been successfully authenticated for SCIM on this subdomain,
+        # so we can assign the corresponding SCIMClient object to request.user - which
+        # will allow this request to pass request.user.is_authenticated checks from now on,
+        # to be served by the relevant views implemented in django-scim2.
+        request.user = scim_client
+        return None
diff --git a/zerver/migrations/0367_scimclient.py b/zerver/migrations/0367_scimclient.py
new file mode 100644
index 0000000000..5d9a38c817
--- /dev/null
+++ b/zerver/migrations/0367_scimclient.py
@@ -0,0 +1,38 @@
+# Generated by Django 3.2.7 on 2021-10-03 18:04
+
+import django.db.models.deletion
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ("zerver", "0366_group_group_membership"),
+    ]
+
+    operations = [
+        migrations.CreateModel(
+            name="SCIMClient",
+            fields=[
+                (
+                    "id",
+                    models.AutoField(
+                        auto_created=True, primary_key=True, serialize=False, verbose_name="ID"
+                    ),
+                ),
+                (
+                    "name",
+                    models.TextField(),
+                ),
+                (
+                    "realm",
+                    models.ForeignKey(
+                        on_delete=django.db.models.deletion.CASCADE, to="zerver.realm"
+                    ),
+                ),
+            ],
+            options={
+                "unique_together": {("realm", "name")},
+            },
+        ),
+    ]
diff --git a/zerver/models.py b/zerver/models.py
index 89824ffafe..6580bc3e6a 100644
--- a/zerver/models.py
+++ b/zerver/models.py
@@ -4184,3 +4184,26 @@ def flush_alert_word(*, instance: AlertWord, **kwargs: object) -> None:
 
 post_save.connect(flush_alert_word, sender=AlertWord)
 post_delete.connect(flush_alert_word, sender=AlertWord)
+
+
+class SCIMClient(models.Model):
+    realm: Realm = models.ForeignKey(Realm, on_delete=CASCADE)
+    name: str = models.TextField()
+
+    class Meta:
+        unique_together = ("realm", "name")
+
+    def __str__(self) -> str:
+        return f"<SCIMClient {self.name} for realm {self.realm_id}>"
+
+    def format_requestor_for_logs(self) -> str:
+        return f"scim-client:{self.name}:realm:{self.realm_id}"
+
+    @property
+    def is_authenticated(self) -> bool:
+        """
+        The purpose of this is to make SCIMClient behave like a UserProfile
+        when an instance is assigned to request.user - we need it to pass
+        request.user.is_authenticated verifications.
+        """
+        return True
diff --git a/zerver/tests/test_scim.py b/zerver/tests/test_scim.py
new file mode 100644
index 0000000000..78af14fee1
--- /dev/null
+++ b/zerver/tests/test_scim.py
@@ -0,0 +1,610 @@
+import copy
+from contextlib import contextmanager
+from typing import Any, Dict, Iterator, Mapping
+from unittest import mock
+
+import orjson
+from django.conf import settings
+from django.http import HttpResponse
+
+from zerver.lib.actions import do_change_full_name
+from zerver.lib.test_classes import ZulipTestCase
+from zerver.models import SCIMClient, UserProfile, get_realm
+
+
+class SCIMTestCase(ZulipTestCase):
+    def setUp(self) -> None:
+        super().setUp()
+        self.realm = get_realm("zulip")
+        self.scim_client = SCIMClient.objects.create(
+            realm=self.realm, name=settings.SCIM_CONFIG["zulip"]["scim_client_name"]
+        )
+
+    def scim_headers(self) -> Mapping[str, str]:
+        return {"HTTP_AUTHORIZATION": f"Bearer {settings.SCIM_CONFIG['zulip']['bearer_token']}"}
+
+    def generate_user_schema(self, user_profile: UserProfile) -> Dict[str, Any]:
+        return {
+            "schemas": ["urn:ietf:params:scim:schemas:core:2.0:User"],
+            "id": user_profile.id,
+            "userName": user_profile.delivery_email,
+            "name": {"formatted": user_profile.full_name},
+            "displayName": user_profile.full_name,
+            "active": True,
+            "meta": {
+                "resourceType": "User",
+                "created": user_profile.date_joined.isoformat(),
+                "lastModified": user_profile.date_joined.isoformat(),
+                "location": f"http://zulip.testserver/scim/v2/Users/{user_profile.id}",
+            },
+        }
+
+    def assert_uniqueness_error(self, result: HttpResponse, extra_message: str) -> None:
+        self.assertEqual(result.status_code, 409)
+        output_data = orjson.loads(result.content)
+
+        expected_response_schema = {
+            "schemas": ["urn:ietf:params:scim:api:messages:2.0:Error"],
+            "detail": f"Email address already in use: {extra_message}",
+            "status": 409,
+            "scimType": "uniqueness",
+        }
+        self.assertEqual(output_data, expected_response_schema)
+
+    @contextmanager
+    def mock_name_formatted_included(self, value: bool) -> Iterator[None]:
+        config_dict = copy.deepcopy(settings.SCIM_CONFIG)
+        config_dict["zulip"]["name_formatted_included"] = value
+        with self.settings(SCIM_CONFIG=config_dict):
+            yield
+
+
+class TestNonSCIMAPIAccess(SCIMTestCase):
+    def test_scim_client_cant_access_different_apis(self) -> None:
+        """
+        Verify that the SCIM client credentials can't be used to get
+        authenticated for non-SCIM API.
+        """
+        hamlet = self.example_user("hamlet")
+
+        # First verify validate_scim_bearer_token doesn't even get called,
+        # as verification of SCIM credentials shouldn't even be attempted,
+        # because we're not querying a SCIM endpoint.
+        with mock.patch("zerver.middleware.validate_scim_bearer_token", return_value=None) as m:
+            result = self.client_get(f"/api/v1/users/{hamlet.id}", **self.scim_headers())
+
+        # The SCIM format of the Authorization header (bearer token) is rejected as a bad request
+        # by our regular API authentication logic.
+        self.assert_json_error(result, "This endpoint requires HTTP basic authentication.", 400)
+        m.assert_not_called()
+
+        # Now simply test end-to-end that access gets denied, without any mocking
+        # interfering with the process.
+        result = self.client_get(f"/api/v1/users/{hamlet.id}", **self.scim_headers())
+        self.assert_json_error(result, "This endpoint requires HTTP basic authentication.", 400)
+
+
+class TestSCIMUser(SCIMTestCase):
+    def test_get_by_id(self) -> None:
+        hamlet = self.example_user("hamlet")
+        expected_response_schema = self.generate_user_schema(hamlet)
+
+        result = self.client_get(f"/scim/v2/Users/{hamlet.id}", **self.scim_headers())
+
+        self.assertEqual(result.status_code, 200)
+        output_data = orjson.loads(result.content)
+        self.assertEqual(output_data, expected_response_schema)
+
+    def test_get_basic_filter_by_username(self) -> None:
+        hamlet = self.example_user("hamlet")
+
+        expected_response_schema = {
+            "schemas": ["urn:ietf:params:scim:api:messages:2.0:ListResponse"],
+            "totalResults": 1,
+            "itemsPerPage": 50,
+            "startIndex": 1,
+            "Resources": [self.generate_user_schema(hamlet)],
+        }
+
+        result = self.client_get(
+            f'/scim/v2/Users?filter=userName eq "{hamlet.delivery_email}"', **self.scim_headers()
+        )
+        self.assertEqual(result.status_code, 200)
+        output_data = orjson.loads(result.content)
+        self.assertEqual(output_data, expected_response_schema)
+
+        # Now we verify the filter feature doesn't allow access to users
+        # on different subdomains.
+        different_realm_user = self.mit_user("starnine")
+        self.assertNotEqual(different_realm_user.realm_id, hamlet.realm_id)
+
+        result = self.client_get(
+            f'/scim/v2/Users?filter=userName eq "{different_realm_user.delivery_email}"',
+            **self.scim_headers(),
+        )
+        self.assertEqual(result.status_code, 200)
+        output_data = orjson.loads(result.content)
+
+        expected_empty_results_response_schema = {
+            "schemas": ["urn:ietf:params:scim:api:messages:2.0:ListResponse"],
+            "totalResults": 0,
+            "itemsPerPage": 50,
+            "startIndex": 1,
+            "Resources": [],
+        }
+
+        self.assertEqual(output_data, expected_empty_results_response_schema)
+
+    def test_get_all_with_pagination(self) -> None:
+        realm = get_realm("zulip")
+
+        result_all = self.client_get("/scim/v2/Users", **self.scim_headers())
+        self.assertEqual(result_all.status_code, 200)
+        output_data_all = orjson.loads(result_all.content)
+
+        expected_response_schema = {
+            "schemas": ["urn:ietf:params:scim:api:messages:2.0:ListResponse"],
+            "totalResults": UserProfile.objects.filter(realm=realm, is_bot=False).count(),
+            "itemsPerPage": 50,
+            "startIndex": 1,
+            "Resources": [],
+        }
+        for user_profile in UserProfile.objects.filter(realm=realm, is_bot=False).order_by("id"):
+            user_schema = self.generate_user_schema(user_profile)
+            expected_response_schema["Resources"].append(user_schema)
+
+        self.assertEqual(output_data_all, expected_response_schema)
+
+        # Test pagination works, as defined in https://datatracker.ietf.org/doc/html/rfc7644#section-3.4.2.4
+        result_offset_limited = self.client_get(
+            "/scim/v2/Users?startIndex=4&count=3", **self.scim_headers()
+        )
+        self.assertEqual(result_offset_limited.status_code, 200)
+        output_data_offset_limited = orjson.loads(result_offset_limited.content)
+        self.assertEqual(output_data_offset_limited["itemsPerPage"], 3)
+        self.assertEqual(output_data_offset_limited["startIndex"], 4)
+        self.assertEqual(
+            output_data_offset_limited["totalResults"], output_data_all["totalResults"]
+        )
+        self.assert_length(output_data_offset_limited["Resources"], 3)
+
+        self.assertEqual(output_data_offset_limited["Resources"], output_data_all["Resources"][3:6])
+
+    def test_get_user_with_no_name_formatted_included_config(self) -> None:
+        """
+        Some clients don't support name.formatted and rely and name.givenName and name.familyName.
+        We have the name_formatted_included configuration option for it for supporting that
+        behavior. Here we test the return dict representation of the User has the appropriate
+        format and values.
+        """
+        hamlet = self.example_user("hamlet")
+        do_change_full_name(hamlet, "Firstname Lastname", acting_user=None)
+        expected_response_schema = self.generate_user_schema(hamlet)
+        expected_response_schema["name"] = {"givenName": "Firstname", "familyName": "Lastname"}
+
+        with self.mock_name_formatted_included(False):
+            result = self.client_get(f"/scim/v2/Users/{hamlet.id}", **self.scim_headers())
+
+        self.assertEqual(result.status_code, 200)
+        output_data = orjson.loads(result.content)
+        self.assertEqual(output_data, expected_response_schema)
+
+        do_change_full_name(hamlet, "Firstnameonly", acting_user=None)
+        expected_response_schema = self.generate_user_schema(hamlet)
+        expected_response_schema["name"] = {"givenName": "Firstnameonly", "familyName": ""}
+
+        with self.mock_name_formatted_included(False):
+            result = self.client_get(f"/scim/v2/Users/{hamlet.id}", **self.scim_headers())
+
+        self.assertEqual(result.status_code, 200)
+        output_data = orjson.loads(result.content)
+        self.assertEqual(output_data, expected_response_schema)
+
+    def test_post(self) -> None:
+        # A payload for creating a new user with the specified account details.
+        payload = {
+            "schemas": ["urn:ietf:params:scim:schemas:core:2.0:User"],
+            "userName": "newuser@zulip.com",
+            "name": {"formatted": "New User", "givenName": "New", "familyName": "User"},
+            "active": True,
+        }
+
+        original_user_count = UserProfile.objects.count()
+        result = self.client_post(
+            "/scim/v2/Users", payload, content_type="application/json", **self.scim_headers()
+        )
+
+        self.assertEqual(result.status_code, 201)
+        output_data = orjson.loads(result.content)
+
+        new_user_count = UserProfile.objects.count()
+        self.assertEqual(new_user_count, original_user_count + 1)
+
+        new_user = UserProfile.objects.last()
+        self.assertEqual(new_user.delivery_email, "newuser@zulip.com")
+        self.assertEqual(new_user.full_name, "New User")
+
+        expected_response_schema = self.generate_user_schema(new_user)
+        self.assertEqual(output_data, expected_response_schema)
+
+    def test_post_with_no_name_formatted_included_config(self) -> None:
+        # A payload for creating a new user with the specified account details.
+        payload = {
+            "schemas": ["urn:ietf:params:scim:schemas:core:2.0:User"],
+            "userName": "newuser@zulip.com",
+            "name": {"givenName": "New", "familyName": "User"},
+            "active": True,
+        }
+
+        original_user_count = UserProfile.objects.count()
+        with self.mock_name_formatted_included(False):
+            result = self.client_post(
+                "/scim/v2/Users", payload, content_type="application/json", **self.scim_headers()
+            )
+
+        self.assertEqual(result.status_code, 201)
+        output_data = orjson.loads(result.content)
+
+        new_user_count = UserProfile.objects.count()
+        self.assertEqual(new_user_count, original_user_count + 1)
+
+        new_user = UserProfile.objects.last()
+        self.assertEqual(new_user.delivery_email, "newuser@zulip.com")
+        self.assertEqual(new_user.full_name, "New User")
+
+        expected_response_schema = self.generate_user_schema(new_user)
+        expected_response_schema["name"] = {"givenName": "New", "familyName": "User"}
+        self.assertEqual(output_data, expected_response_schema)
+
+    def test_post_email_exists(self) -> None:
+        hamlet = self.example_user("hamlet")
+        # A payload for creating a new user with an email that already exists. Thus
+        # this should fail.
+        payload = {
+            "schemas": ["urn:ietf:params:scim:schemas:core:2.0:User"],
+            "userName": hamlet.delivery_email,
+            "name": {"formatted": "New User", "givenName": "New", "familyName": "User"},
+            "active": True,
+        }
+
+        result = self.client_post(
+            "/scim/v2/Users", payload, content_type="application/json", **self.scim_headers()
+        )
+        self.assert_uniqueness_error(result, f"['{hamlet.delivery_email} already has an account']")
+
+    def test_post_name_attribute_missing(self) -> None:
+        # A payload for creating a new user without a name, which should make this request fail.
+        payload = {
+            "schemas": ["urn:ietf:params:scim:schemas:core:2.0:User"],
+            "userName": "newuser@zulip.com",
+            "active": True,
+        }
+
+        result = self.client_post(
+            "/scim/v2/Users", payload, content_type="application/json", **self.scim_headers()
+        )
+        response_dict = result.json()
+        self.assertEqual(
+            response_dict,
+            {
+                "schemas": ["urn:ietf:params:scim:api:messages:2.0:Error"],
+                "detail": "Must specify name.formatted, name.givenName or name.familyName when creating a new user",
+                "status": 400,
+            },
+        )
+
+    def test_post_active_set_to_false(self) -> None:
+        # A payload for creating a new user with is_active=False, which is an invalid operation.
+        payload = {
+            "schemas": ["urn:ietf:params:scim:schemas:core:2.0:User"],
+            "userName": "newuser@zulip.com",
+            "name": {"formatted": "New User", "givenName": "New", "familyName": "User"},
+            "active": False,
+        }
+
+        result = self.client_post(
+            "/scim/v2/Users", payload, content_type="application/json", **self.scim_headers()
+        )
+        response_dict = result.json()
+        self.assertEqual(
+            response_dict,
+            {
+                "schemas": ["urn:ietf:params:scim:api:messages:2.0:Error"],
+                "detail": "New user must have active=True",
+                "status": 400,
+            },
+        )
+
+    def test_post_email_domain_not_allow(self) -> None:
+        realm = get_realm("zulip")
+        realm.emails_restricted_to_domains = True
+        realm.save(update_fields=["emails_restricted_to_domains"])
+
+        # A payload for creating a new user with the specified details.
+        payload = {
+            "schemas": ["urn:ietf:params:scim:schemas:core:2.0:User"],
+            "userName": "newuser@acme.com",
+            "name": {"formatted": "New User", "givenName": "New", "familyName": "User"},
+            "active": True,
+        }
+
+        result = self.client_post(
+            "/scim/v2/Users", payload, content_type="application/json", **self.scim_headers()
+        )
+        response_dict = result.json()
+        self.assertEqual(
+            response_dict,
+            {
+                "schemas": ["urn:ietf:params:scim:api:messages:2.0:Error"],
+                "detail": "This email domain isn't allowed in this organization.",
+                "status": 400,
+            },
+        )
+
+    def test_post_to_try_creating_new_user_on_different_subdomain(self) -> None:
+        # A payload for creating a new user with the specified details.
+        payload = {
+            "schemas": ["urn:ietf:params:scim:schemas:core:2.0:User"],
+            "userName": "newuser@acme.com",
+            "name": {"formatted": "New User", "givenName": "New", "familyName": "User"},
+            "active": True,
+        }
+
+        # Now we make the SCIM request to a different subdomain than our credentials
+        # are configured for. Unauthorized is the expected response.
+        result = self.client_post(
+            "/scim/v2/Users",
+            payload,
+            content_type="application/json",
+            subdomain="lear",
+            **self.scim_headers(),
+        )
+        self.assertEqual(result.status_code, 401)
+
+    def test_delete(self) -> None:
+        hamlet = self.example_user("hamlet")
+        result = self.client_delete(f"/scim/v2/Users/{hamlet.id}", **self.scim_headers())
+
+        expected_response_schema = {
+            "schemas": ["urn:ietf:params:scim:api:messages:2.0:Error"],
+            "detail": 'DELETE operation not supported. Use PUT or PATCH to modify the "active" attribute instead.',
+            "status": 400,
+        }
+
+        self.assertEqual(result.status_code, 400)
+        output_data = orjson.loads(result.content)
+        self.assertEqual(output_data, expected_response_schema)
+
+    def test_put_change_email_and_name(self) -> None:
+        hamlet = self.example_user("hamlet")
+        # PUT replaces all specified attributes of the user. Thus,
+        # this payload will replace hamlet's account details with the new ones,
+        # as specified.
+        payload = {
+            "schemas": ["urn:ietf:params:scim:schemas:core:2.0:User"],
+            "id": hamlet.id,
+            "userName": "bjensen@zulip.com",
+            "name": {
+                "formatted": "Ms. Barbara J Jensen III",
+                "familyName": "Jensen",
+                "givenName": "Barbara",
+                "middleName": "Jane",
+            },
+        }
+        result = self.json_put(f"/scim/v2/Users/{hamlet.id}", payload, **self.scim_headers())
+        self.assertEqual(result.status_code, 200)
+
+        hamlet.refresh_from_db()
+        self.assertEqual(hamlet.delivery_email, "bjensen@zulip.com")
+        self.assertEqual(hamlet.full_name, "Ms. Barbara J Jensen III")
+
+        output_data = orjson.loads(result.content)
+        expected_response_schema = self.generate_user_schema(hamlet)
+        self.assertEqual(output_data, expected_response_schema)
+
+    def test_put_change_name_only(self) -> None:
+        hamlet = self.example_user("hamlet")
+        hamlet_email = hamlet.delivery_email
+        # This payload specified hamlet's current email to not change this attribute,
+        # and only alters the name.
+        payload = {
+            "schemas": ["urn:ietf:params:scim:schemas:core:2.0:User"],
+            "id": hamlet.id,
+            "userName": hamlet_email,
+            "name": {
+                "formatted": "Ms. Barbara J Jensen III",
+                "familyName": "Jensen",
+                "givenName": "Barbara",
+                "middleName": "Jane",
+            },
+        }
+        result = self.json_put(f"/scim/v2/Users/{hamlet.id}", payload, **self.scim_headers())
+        self.assertEqual(result.status_code, 200)
+
+        hamlet.refresh_from_db()
+        self.assertEqual(hamlet.delivery_email, hamlet_email)
+        self.assertEqual(hamlet.full_name, "Ms. Barbara J Jensen III")
+
+        output_data = orjson.loads(result.content)
+        expected_response_schema = self.generate_user_schema(hamlet)
+        self.assertEqual(output_data, expected_response_schema)
+
+    def test_put_email_exists(self) -> None:
+        hamlet = self.example_user("hamlet")
+        cordelia = self.example_user("cordelia")
+        # This payload will attempt to change hamlet's email to cordelia's email.
+        # That would would violate email uniqueness of course, so should fail.
+        payload = {
+            "schemas": ["urn:ietf:params:scim:schemas:core:2.0:User"],
+            "id": hamlet.id,
+            "userName": cordelia.delivery_email,
+            "name": {
+                "formatted": "Ms. Barbara J Jensen III",
+                "familyName": "Jensen",
+                "givenName": "Barbara",
+                "middleName": "Jane",
+            },
+        }
+        result = self.json_put(f"/scim/v2/Users/{hamlet.id}", payload, **self.scim_headers())
+        self.assert_uniqueness_error(
+            result, f"['{cordelia.delivery_email} already has an account']"
+        )
+
+    def test_put_deactivate_reactivate_user(self) -> None:
+        hamlet = self.example_user("hamlet")
+        # This payload flips the active attribute to deactivate the user.
+        payload = {
+            "schemas": ["urn:ietf:params:scim:schemas:core:2.0:User"],
+            "id": hamlet.id,
+            "userName": hamlet.delivery_email,
+            "active": False,
+        }
+        result = self.json_put(f"/scim/v2/Users/{hamlet.id}", payload, **self.scim_headers())
+        self.assertEqual(result.status_code, 200)
+
+        hamlet.refresh_from_db()
+        self.assertEqual(hamlet.is_active, False)
+
+        # We modify the active attribute in the payload to cause reactivation of the user.
+        payload["active"] = True
+        result = self.json_put(f"/scim/v2/Users/{hamlet.id}", payload, **self.scim_headers())
+        self.assertEqual(result.status_code, 200)
+
+        hamlet.refresh_from_db()
+        self.assertEqual(hamlet.is_active, True)
+
+    def test_patch_with_path(self) -> None:
+        hamlet = self.example_user("hamlet")
+        # Payload for a PATCH request to change the user's email to the specified value.
+        payload = {
+            "schemas": ["urn:ietf:params:scim:api:messages:2.0:PatchOp"],
+            "Operations": [{"op": "replace", "path": "userName", "value": "hamlet_new@zulip.com"}],
+        }
+
+        result = self.json_patch(f"/scim/v2/Users/{hamlet.id}", payload, **self.scim_headers())
+        self.assertEqual(result.status_code, 200)
+
+        hamlet.refresh_from_db()
+        self.assertEqual(hamlet.delivery_email, "hamlet_new@zulip.com")
+
+        output_data = orjson.loads(result.content)
+        expected_response_schema = self.generate_user_schema(hamlet)
+        self.assertEqual(output_data, expected_response_schema)
+
+        # Multiple operations:
+        # This payload changes the user's email and name to the specified values.
+        payload = {
+            "schemas": ["urn:ietf:params:scim:api:messages:2.0:PatchOp"],
+            "Operations": [
+                {"op": "replace", "path": "userName", "value": "hamlet_new2@zulip.com"},
+                {"op": "replace", "path": "name.formatted", "value": "New Name"},
+            ],
+        }
+        result = self.json_patch(f"/scim/v2/Users/{hamlet.id}", payload, **self.scim_headers())
+        self.assertEqual(result.status_code, 200)
+
+        hamlet.refresh_from_db()
+        self.assertEqual(hamlet.full_name, "New Name")
+        self.assertEqual(hamlet.delivery_email, "hamlet_new2@zulip.com")
+
+        output_data = orjson.loads(result.content)
+        expected_response_schema = self.generate_user_schema(hamlet)
+        self.assertEqual(output_data, expected_response_schema)
+
+    def test_patch_without_path(self) -> None:
+        """
+        PATCH requests can also specify Operations in a different form,
+        without specifying the "path" op attribute and instead specifying
+        the user attribute to modify in the "value" dict.
+        """
+
+        hamlet = self.example_user("hamlet")
+        # This payload changes the user's email to the specified value.
+        payload = {
+            "schemas": ["urn:ietf:params:scim:api:messages:2.0:PatchOp"],
+            "Operations": [{"op": "replace", "value": {"userName": "hamlet_new@zulip.com"}}],
+        }
+
+        result = self.json_patch(f"/scim/v2/Users/{hamlet.id}", payload, **self.scim_headers())
+        self.assertEqual(result.status_code, 200)
+
+        hamlet.refresh_from_db()
+        self.assertEqual(hamlet.delivery_email, "hamlet_new@zulip.com")
+
+        output_data = orjson.loads(result.content)
+        expected_response_schema = self.generate_user_schema(hamlet)
+        self.assertEqual(output_data, expected_response_schema)
+
+    def test_patch_deactivate_reactivate_user(self) -> None:
+        hamlet = self.example_user("hamlet")
+        # Payload for a PATCH request to deactivate the user.
+        payload = {
+            "schemas": ["urn:ietf:params:scim:api:messages:2.0:PatchOp"],
+            "Operations": [{"op": "replace", "path": "active", "value": False}],
+        }
+
+        result = self.json_patch(f"/scim/v2/Users/{hamlet.id}", payload, **self.scim_headers())
+        self.assertEqual(result.status_code, 200)
+
+        hamlet.refresh_from_db()
+        self.assertEqual(hamlet.is_active, False)
+
+        # Payload for a PATCH request to reactivate the user.
+        payload = {
+            "schemas": ["urn:ietf:params:scim:api:messages:2.0:PatchOp"],
+            "Operations": [{"op": "replace", "path": "active", "value": True}],
+        }
+        result = self.json_patch(f"/scim/v2/Users/{hamlet.id}", payload, **self.scim_headers())
+        self.assertEqual(result.status_code, 200)
+        hamlet.refresh_from_db()
+        self.assertEqual(hamlet.is_active, True)
+
+    def test_patch_unsupported_attribute(self) -> None:
+        hamlet = self.example_user("hamlet")
+        # Payload for a PATCH request to change the middle name of the user - which is not supported.
+        payload = {
+            "schemas": ["urn:ietf:params:scim:api:messages:2.0:PatchOp"],
+            "Operations": [{"op": "replace", "path": "name.middleName", "value": "John"}],
+        }
+
+        with self.assertLogs("django.request", "ERROR") as m:
+            result = self.json_patch(f"/scim/v2/Users/{hamlet.id}", payload, **self.scim_headers())
+            self.assertEqual(
+                result.json(),
+                {
+                    "schemas": ["urn:ietf:params:scim:api:messages:2.0:Error"],
+                    "detail": "Not Implemented",
+                    "status": 501,
+                },
+            )
+            self.assertEqual(
+                m.output, [f"ERROR:django.request:Not Implemented: /scim/v2/Users/{hamlet.id}"]
+            )
+
+
+class TestSCIMGroup(SCIMTestCase):
+    """
+    SCIM groups aren't implemented yet. An implementation will modify this class
+    to actually test desired behavior.
+    """
+
+    def test_endpoints_disabled(self) -> None:
+        with self.assertLogs("django.request", "ERROR") as m:
+            result = self.client_get("/scim/v2/Groups", **self.scim_headers())
+            self.assertEqual(result.status_code, 501)
+            self.assertEqual(m.output, ["ERROR:django.request:Not Implemented: /scim/v2/Groups"])
+        with self.assertLogs("django.request", "ERROR") as m:
+            result = self.client_get("/scim/v2/Groups/1", **self.scim_headers())
+            self.assertEqual(result.status_code, 501)
+            self.assertEqual(m.output, ["ERROR:django.request:Not Implemented: /scim/v2/Groups/1"])
+        with self.assertLogs("django.request", "ERROR") as m:
+            result = self.client_post(
+                "/scim/v2/Groups/.search",
+                {},
+                content_type="application/json",
+                **self.scim_headers(),
+            )
+            self.assertEqual(result.status_code, 501)
+            self.assertEqual(
+                m.output, ["ERROR:django.request:Not Implemented: /scim/v2/Groups/.search"]
+            )
diff --git a/zproject/computed_settings.py b/zproject/computed_settings.py
index 1b1c2fee2f..a40b2990fc 100644
--- a/zproject/computed_settings.py
+++ b/zproject/computed_settings.py
@@ -187,6 +187,7 @@ MIDDLEWARE = (
     "zerver.middleware.HostDomainMiddleware",
     "django.middleware.csrf.CsrfViewMiddleware",
     "django.contrib.auth.middleware.AuthenticationMiddleware",
+    "zerver.middleware.ZulipSCIMAuthCheckMiddleware",
     # Make sure 2FA middlewares come after authentication middleware.
     "django_otp.middleware.OTPMiddleware",  # Required by two factor auth.
     "two_factor.middleware.threadlocals.ThreadLocals",  # Required by Twilio
@@ -213,6 +214,7 @@ INSTALLED_APPS = [
     "confirmation",
     "zerver",
     "social_django",
+    "django_scim",
     # 2FA related apps.
     "django_otp",
     "django_otp.plugins.otp_static",
@@ -716,6 +718,7 @@ TRACEMALLOC_DUMP_DIR = zulip_path("/var/log/zulip/tracemalloc")
 DELIVER_SCHEDULED_MESSAGES_LOG_PATH = zulip_path("/var/log/zulip/deliver_scheduled_messages.log")
 RETENTION_LOG_PATH = zulip_path("/var/log/zulip/message_retention.log")
 AUTH_LOG_PATH = zulip_path("/var/log/zulip/auth.log")
+SCIM_LOG_PATH = zulip_path("/var/log/zulip/scim.log")
 
 ZULIP_WORKER_TEST_FILE = "/tmp/zulip-worker-test-file"
 
@@ -817,6 +820,12 @@ LOGGING: Dict[str, Any] = {
             "formatter": "default",
             "filename": LDAP_LOG_PATH,
         },
+        "scim_file": {
+            "level": "DEBUG",
+            "class": "logging.handlers.WatchedFileHandler",
+            "formatter": "default",
+            "filename": SCIM_LOG_PATH,
+        },
         "slow_queries_file": {
             "level": "INFO",
             "class": "logging.handlers.WatchedFileHandler",
@@ -913,6 +922,11 @@ LOGGING: Dict[str, Any] = {
             "handlers": ["console", "ldap_file", "errors_file"],
             "propagate": False,
         },
+        "django_scim": {
+            "level": "DEBUG",
+            "handlers": ["scim_file", "errors_file"],
+            "propagate": False,
+        },
         "pika": {
             # pika is super chatty on INFO.
             "level": "WARNING",
@@ -1194,3 +1208,22 @@ if SENTRY_DSN:
     from .sentry import setup_sentry
 
     setup_sentry(SENTRY_DSN, get_config("machine", "deploy_type", "development"))
+
+SCIM_SERVICE_PROVIDER = {
+    "USER_ADAPTER": "zerver.lib.scim.ZulipSCIMUser",
+    "USER_FILTER_PARSER": "zerver.lib.scim_filter.ZulipUserFilterQuery",
+    # NETLOC is actually overriden by the behavior of base_scim_location_getter,
+    # but django-scim2 requires it to be set, even though it ends up not being used.
+    # So we need to give it some value here, and EXTERNAL_HOST is the most generic.
+    "NETLOC": EXTERNAL_HOST,
+    "SCHEME": EXTERNAL_URI_SCHEME,
+    "GET_EXTRA_MODEL_FILTER_KWARGS_GETTER": "zerver.lib.scim.get_extra_model_filter_kwargs_getter",
+    "BASE_LOCATION_GETTER": "zerver.lib.scim.base_scim_location_getter",
+    "AUTHENTICATION_SCHEMES": [
+        {
+            "type": "bearer",
+            "name": "Bearer",
+            "description": "Bearer token",
+        },
+    ],
+}
diff --git a/zproject/dev_settings.py b/zproject/dev_settings.py
index f39f3e177a..3da5d1fa93 100644
--- a/zproject/dev_settings.py
+++ b/zproject/dev_settings.py
@@ -179,3 +179,11 @@ SOCIAL_AUTH_SAML_SP_ENTITY_ID = "http://localhost:9991"
 SOCIAL_AUTH_SUBDOMAIN = "auth"
 
 MEMCACHED_USERNAME: Optional[str] = None
+
+SCIM_CONFIG = {
+    "zulip": {
+        "bearer_token": "token1234",
+        "scim_client_name": "test-scim-client",
+        "name_formatted_included": True,
+    }
+}
diff --git a/zproject/test_extra_settings.py b/zproject/test_extra_settings.py
index 4dbcac3227..ee8b630ec6 100644
--- a/zproject/test_extra_settings.py
+++ b/zproject/test_extra_settings.py
@@ -271,3 +271,11 @@ RATE_LIMITING_RULES: Dict[str, List[Tuple[int, int]]] = {
 }
 
 FREE_TRIAL_DAYS: Optional[int] = None
+
+SCIM_CONFIG = {
+    "zulip": {
+        "bearer_token": "token1234",
+        "scim_client_name": "test-scim-client",
+        "name_formatted_included": True,
+    }
+}
diff --git a/zproject/urls.py b/zproject/urls.py
index 8dd5c8e0e4..f433dfbef3 100644
--- a/zproject/urls.py
+++ b/zproject/urls.py
@@ -10,7 +10,7 @@ from django.contrib.auth.views import (
     PasswordResetConfirmView,
     PasswordResetDoneView,
 )
-from django.urls import path
+from django.urls import path, re_path
 from django.urls.resolvers import URLPattern, URLResolver
 from django.utils.module_loading import import_string
 from django.views.generic import RedirectView, TemplateView
@@ -740,6 +740,24 @@ urls += [
 urls += [path("", include("social_django.urls", namespace="social"))]
 urls += [path("saml/metadata.xml", saml_sp_metadata)]
 
+# SCIM2
+
+from django_scim import views as scim_views
+
+urls += [
+    # These first couple entries mark the Groups feature of SCIM as
+    # something we haven't implemented.
+    re_path(
+        r"^scim/v2/Groups/.search$",
+        scim_views.SCIMView.as_view(implemented=False),
+    ),
+    re_path(
+        r"^scim/v2/Groups(?:/(?P<uuid>[^/]+))?$",
+        scim_views.SCIMView.as_view(implemented=False),
+    ),
+    path("scim/v2/", include("django_scim.urls", namespace="scim")),
+]
+
 # User documentation site
 help_documentation_view = MarkdownDirectoryView.as_view(
     template_name="zerver/documentation_main.html", path_template="/zerver/help/%s.md"