diff --git a/public/openapi/write.yaml b/public/openapi/write.yaml
index d08236d274..6e5904cbf2 100644
--- a/public/openapi/write.yaml
+++ b/public/openapi/write.yaml
@@ -226,6 +226,8 @@ paths:
     $ref: 'write/flags/flagId/notes/datetime.yaml'
   /search/categories:
     $ref: 'write/search/categories.yaml'
+  /search/chats/{roomId}/users:
+    $ref: 'write/search/chats/roomId/users.yaml'
   /admin/settings/{setting}:
     $ref: 'write/admin/settings/setting.yaml'
   /admin/analytics:
diff --git a/public/openapi/write/search/chats/roomId/users.yaml b/public/openapi/write/search/chats/roomId/users.yaml
new file mode 100644
index 0000000000..dd94a88d02
--- /dev/null
+++ b/public/openapi/write/search/chats/roomId/users.yaml
@@ -0,0 +1,44 @@
+get:
+  tags:
+    - search
+  summary: find room users by keyword
+  description: This operation returns a set of users in a chat room matching the keyword search.
+  parameters:
+    - in: path
+      name: roomId
+      schema:
+        type: number
+      required: true
+      description: room ID to check
+      example: 1
+    - in: query
+      name: 'query'
+      schema:
+        type: string
+      required: false
+      description: The keyword used in the category search
+      example: 'admin'
+  responses:
+    '200':
+      description: matching users successfully retrieved
+      content:
+        application/json:
+          schema:
+            type: object
+            properties:
+              status:
+                $ref: ../../../../components/schemas/Status.yaml#/Status
+              response:
+                type: object
+                properties:
+                  users:
+                    type: array
+                    items:
+                      allOf:
+                        - $ref: ../../../../components/schemas/UserObject.yaml#/UserObjectSlim
+                        - type: object
+                          properties:
+                            isOwner:
+                              type: boolean
+                            canKick:
+                              type: boolean
\ No newline at end of file
diff --git a/public/src/client/chats/user-list.js b/public/src/client/chats/user-list.js
index a4bd77cf65..36c6267cea 100644
--- a/public/src/client/chats/user-list.js
+++ b/public/src/client/chats/user-list.js
@@ -72,11 +72,8 @@ define('forum/chats/user-list', ['api'], function (api) {
 
 	userList.addSearchHandler = function (roomId, inputEl, callback) {
 		inputEl.on('keyup', utils.debounce(async () => {
-			const username = inputEl.val();
-			const data = await socket.emit('modules.chats.searchMembers', {
-				username: username,
-				roomId: roomId,
-			});
+			const query = inputEl.val();
+			const data = await api.get(`/search/chats/${roomId}/users`, { query });
 			callback(data);
 		}, 200));
 	};
diff --git a/src/api/search.js b/src/api/search.js
index ac77347c26..043c97176e 100644
--- a/src/api/search.js
+++ b/src/api/search.js
@@ -2,7 +2,9 @@
 
 const _ = require('lodash');
 
+const user = require('../user');
 const categories = require('../categories');
+const messaging = require('../messaging');
 const privileges = require('../privileges');
 const meta = require('../meta');
 const plugins = require('../plugins');
@@ -103,3 +105,50 @@ async function loadCids(uid, parentCid) {
 	await getCidsRecursive(pageCids);
 	return resultCids;
 }
+
+searchApi.roomUsers = async (caller, { query, roomId }) => {
+	const [isAdmin, inRoom, isRoomOwner] = await Promise.all([
+		user.isAdministrator(caller.uid),
+		messaging.isUserInRoom(caller.uid, roomId),
+		messaging.isRoomOwner(caller.uid, roomId),
+	]);
+
+	if (!isAdmin && !inRoom) {
+		throw new Error('[[error:no-privileges]]');
+	}
+
+	const results = await user.search({
+		query,
+		paginate: false,
+		hardCap: -1,
+		uid: caller.uid,
+	});
+
+	const { users } = results;
+	const foundUids = users.map(user => user && user.uid);
+	const isUidInRoom = _.zipObject(
+		foundUids,
+		await messaging.isUsersInRoom(foundUids, roomId)
+	);
+
+	const roomUsers = users.filter(user => isUidInRoom[user.uid]);
+	const isOwners = await messaging.isRoomOwner(roomUsers.map(u => u.uid), roomId);
+
+	roomUsers.forEach((user, index) => {
+		if (user) {
+			user.isOwner = isOwners[index];
+			user.canKick = isRoomOwner && (parseInt(user.uid, 10) !== parseInt(caller.uid, 10));
+		}
+	});
+
+	roomUsers.sort((a, b) => {
+		if (a.isOwner && !b.isOwner) {
+			return -1;
+		} else if (!a.isOwner && b.isOwner) {
+			return 1;
+		}
+		return 0;
+	});
+
+	return { users: roomUsers };
+};
diff --git a/src/controllers/write/search.js b/src/controllers/write/search.js
index a6acd0a59a..cfdaad44a8 100644
--- a/src/controllers/write/search.js
+++ b/src/controllers/write/search.js
@@ -8,3 +8,8 @@ const Search = module.exports;
 Search.categories = async (req, res) => {
 	helpers.formatApiResponse(200, res, await api.search.categories(req, req.query));
 };
+
+Search.roomUsers = async (req, res) => {
+	const { query } = req.query;
+	helpers.formatApiResponse(200, res, await api.search.roomUsers(req, { query, ...req.params }));
+};
diff --git a/src/routes/write/search.js b/src/routes/write/search.js
index 01b98cdeed..4d4108a05b 100644
--- a/src/routes/write/search.js
+++ b/src/routes/write/search.js
@@ -1,19 +1,20 @@
 'use strict';
 
 const router = require('express').Router();
-// const middleware = require('../../middleware');
+const middleware = require('../../middleware');
 const controllers = require('../../controllers');
 const routeHelpers = require('../helpers');
 
 const { setupApiRoute } = routeHelpers;
 
 module.exports = function () {
-	// const middlewares = [];
+	const middlewares = [middleware.ensureLoggedIn];
 
 	// maybe redirect to /search/posts?
 	// setupApiRoute(router, 'post', '/', [...middlewares], controllers.write.search.TBD);
 
 	setupApiRoute(router, 'get', '/categories', [], controllers.write.search.categories);
+	setupApiRoute(router, 'get', '/chats/:roomId/users', [...middlewares, middleware.checkRequired.bind(null, ['query']), middleware.canChat, middleware.assert.room], controllers.write.search.roomUsers);
 
 	return router;
 };
diff --git a/src/socket.io/modules.js b/src/socket.io/modules.js
index 9901b25c82..910713d9cf 100644
--- a/src/socket.io/modules.js
+++ b/src/socket.io/modules.js
@@ -157,51 +157,16 @@ SocketModules.chats.sortPublicRooms = async function (socket, data) {
 };
 
 SocketModules.chats.searchMembers = async function (socket, data) {
+	sockets.warnDeprecated(socket, 'GET /api/v3/search/chats/:roomId/users?query=');
+
 	if (!data || !data.roomId) {
 		throw new Error('[[error:invalid-data]]');
 	}
-	const [isAdmin, inRoom, isRoomOwner] = await Promise.all([
-		user.isAdministrator(socket.uid),
-		Messaging.isUserInRoom(socket.uid, data.roomId),
-		Messaging.isRoomOwner(socket.uid, data.roomId),
-	]);
 
-	if (!isAdmin && !inRoom) {
-		throw new Error('[[error:no-privileges]]');
-	}
-
-	const results = await user.search({
-		query: data.username,
-		paginate: false,
-		hardCap: -1,
-	});
-
-	const { users } = results;
-	const foundUids = users.map(user => user && user.uid);
-	const isUidInRoom = _.zipObject(
-		foundUids,
-		await Messaging.isUsersInRoom(foundUids, data.roomId)
-	);
-
-	const roomUsers = users.filter(user => isUidInRoom[user.uid]);
-	const isOwners = await Messaging.isRoomOwner(roomUsers.map(u => u.uid), data.roomId);
-
-	roomUsers.forEach((user, index) => {
-		if (user) {
-			user.isOwner = isOwners[index];
-			user.canKick = isRoomOwner && (parseInt(user.uid, 10) !== parseInt(socket.uid, 10));
-		}
-	});
-
-	roomUsers.sort((a, b) => {
-		if (a.isOwner && !b.isOwner) {
-			return -1;
-		} else if (!a.isOwner && b.isOwner) {
-			return 1;
-		}
-		return 0;
-	});
-	return { users: roomUsers };
+	// parameter renamed; backwards compatibility
+	data.query = data.username;
+	delete data.username;
+	return await api.search.roomUsers(socket, data);
 };
 
 SocketModules.chats.toggleOwner = async (socket, data) => {