How to Send Push Notifications to Specific Users in FlutterFlow

Open FlutterFlow's Action Flow editor for your Main page or initial route's On Page Load event. Add an action: Push Notifications → Request Permission (iOS only — Android grants automatically). Add a second Custom Action named 'saveFcmToken'. This action calls FirebaseMessaging.instance.getToken() to retrieve the current FCM token, then writes it to the authenticated user's Firestore document under the field 'fcmToken' (String) and 'fcmTokenUpdatedAt' (DateTime). FCM tokens can be rotated by the OS — if you only save the token at registration and never refresh it, you'll accumulate stale tokens and miss deliveries.

1// Custom Action: saveFcmToken
2import 'package:firebase_messaging/firebase_messaging.dart';
3import 'package:cloud_firestore/cloud_firestore.dart';
4import 'package:firebase_auth/firebase_auth.dart';
5
6Future<void> saveFcmToken() async {
7  final user = FirebaseAuth.instance.currentUser;
8  if (user == null) return;
9  final token = await FirebaseMessaging.instance.getToken();
10  if (token == null) return;
11  await FirebaseFirestore.instance
12      .collection('users')
13      .doc(user.uid)
14      .update({
15        'fcmToken': token,
16        'fcmTokenUpdatedAt': FieldValue.serverTimestamp(),
17      });
18}

In FlutterFlow, navigate to the Action Flow where you want to trigger a push (e.g., an admin button or an in-app event). Add action: Notifications → Push Notification. In the recipient field, select a Firestore Document Reference — this should be the target user's document from your 'users' collection. Fill in Title and Body using dynamic values from your data. This built-in action reads the fcmToken from the referenced user document and sends via Firebase Cloud Messaging automatically. For notifications triggered by one user's action affecting another user (like a new message), pass the recipient user's document reference through your data flow.

Topics let you send one notification to all users subscribed to a named topic (e.g., 'sports-updates', 'sale-alerts') without managing individual tokens. Create a Custom Action named 'subscribeToTopic' that calls FirebaseMessaging.instance.subscribeToTopic(topicName). Call this action when users opt into interest categories (e.g., in your notification preferences screen). Create a corresponding 'unsubscribeFromTopic' action. To send to a topic, create a Cloud Function (see Step 4) that calls the FCM API with the topic as the target. Topics scale to millions of subscribers — FCM handles the fan-out for you.

1// Custom Actions: subscribeToTopic / unsubscribeFromTopic
2import 'package:firebase_messaging/firebase_messaging.dart';
3
4Future<void> subscribeToTopic(String topicName) async {
5  await FirebaseMessaging.instance.subscribeToTopic(topicName);
6}
7
8Future<void> unsubscribeFromTopic(String topicName) async {
9  await FirebaseMessaging.instance.unsubscribeFromTopic(topicName);
10}

For segment targeting (all inactive users, all premium subscribers, users in a specific city), create a Cloud Function named 'sendSegmentNotification'. The function accepts: segment query parameters, notification title, and body. It queries Firestore for matching users, extracts their fcmToken fields, filters out null/empty tokens, then calls messaging.sendEachForMulticast() — NOT a loop of individual send() calls. sendEachForMulticast accepts up to 500 tokens per call, so paginate your Firestore query in batches of 500. This approach is 50-100x faster than sending one-at-a-time for large user bases.

1// Cloud Function: sendSegmentNotification
2const admin = require('firebase-admin');
3const functions = require('firebase-functions');
4
5admin.initializeApp();
6
7exports.sendSegmentNotification = functions.https.onCall(
8  async (data, context) => {
9    if (!context.auth?.token.admin) {
10      throw new functions.https.HttpsError('permission-denied', 'Admin only');
11    }
12    const { segment, title, body } = data;
13    const db = admin.firestore();
14    let query = db.collection('users').where('fcmToken', '!=', '');
15    if (segment === 'premium') {
16      query = query.where('plan', '==', 'premium');
17    } else if (segment === 'inactive_30d') {
18      const cutoff = new Date(Date.now() - 30 * 24 * 60 * 60 * 1000);
19      query = query.where('lastActiveAt', '<', cutoff);
20    }
21    const snap = await query.get();
22    const tokens = snap.docs
23      .map((d) => d.data().fcmToken)
24      .filter(Boolean);
25    if (tokens.length === 0) return { sent: 0 };
26
27    // Batch in groups of 500
28    const BATCH = 500;
29    let totalSent = 0;
30    for (let i = 0; i < tokens.length; i += BATCH) {
31      const batch = tokens.slice(i, i + BATCH);
32      const res = await admin.messaging().sendEachForMulticast({
33        tokens: batch,
34        notification: { title, body },
35      });
36      totalSent += res.successCount;
37    }
38    return { sent: totalSent };
39  }
40);

Create a new admin-only page in FlutterFlow named 'Send Notification'. Add a Conditional widget at the top to redirect non-admin users. Inside, add: a DropdownButton for segment selection (Individual, Topic, Premium Users, Inactive 30 Days), a TextField for recipient search (for Individual mode, queries users by name/email), a TextField for notification Title, a TextField for notification Body, a character count indicator, and a large Send button. For Individual mode, use FlutterFlow's built-in Push Notification action. For Topic and Segment modes, call the Cloud Function via an API call action, passing the selected segment, title, and body as parameters. Show a success Snackbar with the delivery count on completion.