diff --git a/dejacode/settings.py b/dejacode/settings.py
index 2bc493bf..e210bd42 100644
--- a/dejacode/settings.py
+++ b/dejacode/settings.py
@@ -18,6 +18,8 @@
 from django_auth_ldap.config import GroupOfNamesType
 from django_auth_ldap.config import LDAPSearch
 
+from dejacode_toolkit.ldap import build_user_search
+
 # The home directory of the dejacode user that owns the installation.
 PROJECT_DIR = environ.Path(__file__) - 1
 ROOT_DIR = PROJECT_DIR - 1
@@ -775,7 +777,37 @@ def get_fake_redis_connection(config, use_strict_redis):
 # AUTH_LDAP_USER_FILTERSTR="(uid=%(user)s)"
 AUTH_LDAP_USER_FILTERSTR = env.str("AUTH_LDAP_USER_FILTERSTR", default="")
 
-AUTH_LDAP_USER_SEARCH = LDAPSearch(AUTH_LDAP_USER_DN, ldap.SCOPE_SUBTREE, AUTH_LDAP_USER_FILTERSTR)
+# Optional: Define multiple LDAP user searches using a JSON list.
+# When provided, this setting overrides AUTH_LDAP_USER_DN and AUTH_LDAP_USER_FILTERSTR.
+#
+# Example:
+# AUTH_LDAP_USER_SEARCHES = """
+#     [
+#         {
+#             "base": "ou=users,dc=example,dc=com",
+#             "filter": "(uid=%(user)s)"
+#         },
+#         {
+#             "base": "ou=otherusers,dc=example,dc=com",
+#             "filter": "(uid=%(user)s)"
+#         }
+#     ]
+#     """
+#
+# Hint: use as a single line string within docker env
+#
+# Each entry must define:
+# - "base":   The base DN to search
+# - "filter": The LDAP filter (must include %(user)s)
+#
+# All searches are combined using LDAPSearchUnion.
+AUTH_LDAP_USER_SEARCHES = env.str("AUTH_LDAP_USER_SEARCHES", default="")
+
+AUTH_LDAP_USER_SEARCH = build_user_search(
+    AUTH_LDAP_USER_SEARCHES,
+    AUTH_LDAP_USER_DN,
+    AUTH_LDAP_USER_FILTERSTR,
+)
 
 # When AUTH_LDAP_AUTOCREATE_USER is True (default), a new DejaCode user will be
 # created in the database with the minimum permission (a read-only user).
diff --git a/dejacode_toolkit/ldap.py b/dejacode_toolkit/ldap.py
new file mode 100644
index 00000000..5fc2d7f3
--- /dev/null
+++ b/dejacode_toolkit/ldap.py
@@ -0,0 +1,55 @@
+#
+# Copyright (c) nexB Inc. and others. All rights reserved.
+# DejaCode is a trademark of nexB Inc.
+# SPDX-License-Identifier: AGPL-3.0-only
+# See https://github.com/aboutcode-org/dejacode for support or download.
+# See https://aboutcode.org for more information about AboutCode FOSS projects.
+#
+
+import json
+
+from django.core.exceptions import ImproperlyConfigured
+
+import ldap
+from django_auth_ldap.config import LDAPSearch
+from django_auth_ldap.config import LDAPSearchUnion
+
+
+def build_user_search(user_searches, user_dn, user_filterstr):
+    """
+    Return the ``AUTH_LDAP_USER_SEARCH`` object.
+
+    When ``user_searches`` (a raw JSON string) is provided, parse and validate
+    it and return an ``LDAPSearchUnion``. Otherwise, fall back to a single
+    ``LDAPSearch`` built from ``user_dn`` and ``user_filterstr``.
+    """
+    if not user_searches:
+        return LDAPSearch(user_dn, ldap.SCOPE_SUBTREE, user_filterstr)
+
+    try:
+        definitions = json.loads(user_searches)
+    except json.JSONDecodeError as e:
+        raise ImproperlyConfigured(f"Invalid JSON in AUTH_LDAP_USER_SEARCHES: {e}") from e
+
+    if not isinstance(definitions, list):
+        raise ImproperlyConfigured("AUTH_LDAP_USER_SEARCHES must be a JSON list")
+
+    if not definitions:
+        raise ImproperlyConfigured("AUTH_LDAP_USER_SEARCHES cannot be empty")
+
+    searches = []
+    for index, entry in enumerate(definitions):
+        if not isinstance(entry, dict):
+            raise ImproperlyConfigured(f"AUTH_LDAP_USER_SEARCHES[{index}] must be a JSON object")
+
+        base_dn = entry.get("base")
+        filterstr = entry.get("filter")
+
+        if not base_dn or not filterstr:
+            raise ImproperlyConfigured(
+                f"AUTH_LDAP_USER_SEARCHES[{index}] must define 'base' and 'filter'"
+            )
+
+        searches.append(LDAPSearch(base_dn, ldap.SCOPE_SUBTREE, filterstr))
+
+    return LDAPSearchUnion(*searches)
diff --git a/dje/tests/test_ldap_config.py b/dje/tests/test_ldap_config.py
new file mode 100644
index 00000000..a54500ec
--- /dev/null
+++ b/dje/tests/test_ldap_config.py
@@ -0,0 +1,68 @@
+#
+# Copyright (c) nexB Inc. and others. All rights reserved.
+# DejaCode is a trademark of nexB Inc.
+# SPDX-License-Identifier: AGPL-3.0-only
+# See https://github.com/aboutcode-org/dejacode for support or download.
+# See https://aboutcode.org for more information about AboutCode FOSS projects.
+#
+
+from django.core.exceptions import ImproperlyConfigured
+from django.test import SimpleTestCase
+
+from django_auth_ldap.config import LDAPSearch
+from django_auth_ldap.config import LDAPSearchUnion
+
+from dejacode_toolkit.ldap import build_user_search
+
+
+class BuildUserSearchTestCase(SimpleTestCase):
+    def test_build_user_search_fallback_to_single_search_when_empty(self):
+        result = build_user_search("", "ou=users,dc=example,dc=com", "(uid=%(user)s)")
+        self.assertIsInstance(result, LDAPSearch)
+
+    def test_build_user_search_valid_json_returns_union(self):
+        raw = (
+            '[{"base": "ou=a,dc=example,dc=com", "filter": "(uid=%(user)s)"},'
+            ' {"base": "ou=b,dc=example,dc=com", "filter": "(uid=%(user)s)"}]'
+        )
+        result = build_user_search(raw, "", "")
+        self.assertIsInstance(result, LDAPSearchUnion)
+
+    def test_build_user_search_single_entry_still_returns_union(self):
+        raw = '[{"base": "ou=a,dc=example,dc=com", "filter": "(uid=%(user)s)"}]'
+        result = build_user_search(raw, "", "")
+        self.assertIsInstance(result, LDAPSearchUnion)
+
+    def test_build_user_search_invalid_json_raises(self):
+        with self.assertRaisesMessage(ImproperlyConfigured, "Invalid JSON"):
+            build_user_search("{not json", "", "")
+
+    def test_build_user_search_not_a_list_raises(self):
+        with self.assertRaisesMessage(ImproperlyConfigured, "must be a JSON list"):
+            build_user_search('{"base": "x", "filter": "y"}', "", "")
+
+    def test_build_user_search_empty_list_raises(self):
+        with self.assertRaisesMessage(ImproperlyConfigured, "cannot be empty"):
+            build_user_search("[]", "", "")
+
+    def test_build_user_search_entry_not_object_raises(self):
+        with self.assertRaisesMessage(ImproperlyConfigured, "[0] must be a JSON object"):
+            build_user_search('["not an object"]', "", "")
+
+    def test_build_user_search_missing_base_raises(self):
+        raw = '[{"filter": "(uid=%(user)s)"}]'
+        with self.assertRaisesMessage(ImproperlyConfigured, "[0] must define 'base' and 'filter'"):
+            build_user_search(raw, "", "")
+
+    def test_build_user_search_missing_filter_raises(self):
+        raw = '[{"base": "ou=a,dc=example,dc=com"}]'
+        with self.assertRaisesMessage(ImproperlyConfigured, "[0] must define 'base' and 'filter'"):
+            build_user_search(raw, "", "")
+
+    def test_build_user_search_error_index_points_to_bad_entry(self):
+        raw = (
+            '[{"base": "ou=a,dc=example,dc=com", "filter": "(uid=%(user)s)"},'
+            ' {"base": "ou=b,dc=example,dc=com"}]'
+        )
+        with self.assertRaisesMessage(ImproperlyConfigured, "[1] must define 'base' and 'filter'"):
+            build_user_search(raw, "", "")
diff --git a/docs/application-settings.rst b/docs/application-settings.rst
index d7e1903f..943c9dfe 100644
--- a/docs/application-settings.rst
+++ b/docs/application-settings.rst
@@ -383,6 +383,42 @@ It must return exactly one result for authentication to succeed.
     AUTH_LDAP_USER_DN="ou=users,dc=example,dc=com"
     AUTH_LDAP_USER_FILTERSTR="(uid=%(user)s)"
 
+AUTH_LDAP_USER_SEARCHES
+-----------------------
+
+To search across multiple LDAP locations, use
+``AUTH_LDAP_USER_SEARCHES``.
+
+When this setting is provided, it overrides both
+``AUTH_LDAP_USER_DN`` and ``AUTH_LDAP_USER_FILTERSTR``.
+
+The setting must contain a JSON list of search definitions. Each entry
+must define:
+
+- ``base``: The base DN to search
+- ``filter``: The LDAP filter (must include ``%(user)s``)
+
+All configured searches are combined using ``LDAPSearchUnion``.
+
+Example:
+
+.. code-block:: python
+
+    AUTH_LDAP_USER_SEARCHES = """
+    [
+        {
+            "base": "ou=users,dc=example,dc=com",
+            "filter": "(uid=%(user)s)"
+        },
+        {
+            "base": "ou=otherusers,dc=example,dc=com",
+            "filter": "(uid=%(user)s)"
+        }
+    ]
+    """
+
+For usage in a ``docker.env`` file only a single line string is accepted.
+
 AUTOCREATE_USER
 ---------------