How to Send Push Notifications to Groups of Users in FlutterFlow

Before you can target groups you need every user's current FCM token saved in Firestore. In FlutterFlow open your app's initial action flow (typically triggered on the splash or home page load). Add a Custom Action that calls FirebaseMessaging.instance.getToken() and writes the result into the current user's Firestore document under the field fcmToken. Also store a lastSeen timestamp and any segment fields such as plan, region, or interests as an array. This document becomes the source of truth for all group targeting.

1// Custom Action: updateFcmToken.dart
2import 'package:firebase_messaging/firebase_messaging.dart';
3import 'package:cloud_firestore/cloud_firestore.dart';
4import 'package:firebase_auth/firebase_auth.dart';
5
6Future updateFcmToken() async {
7  final token = await FirebaseMessaging.instance.getToken();
8  final uid = FirebaseAuth.instance.currentUser?.uid;
9  if (uid != null && token != null) {
10    await FirebaseFirestore.instance.collection('users').doc(uid).update({
11      'fcmToken': token,
12      'lastSeen': FieldValue.serverTimestamp(),
13    });
14  }
15}

FCM topics are the simplest broadcast mechanism. A device subscribes to a named string topic, and any message sent to that topic is delivered to all subscribers. In FlutterFlow create a Custom Action called subscribeToTopic. Call FirebaseMessaging.instance.subscribeToTopic(topicName). Trigger this action from your onboarding flow when users select interests (sports, deals, news) or when they opt into a role-based group (admins, beta-testers). Add matching unsubscribeFromTopic actions on your notification preferences screen so users can opt out without you needing to maintain a token list.

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

Give users control by building a Preferences page in FlutterFlow. Add a Column with one Row per topic: a Text label ('Promotions', 'New Features', 'Regional Updates') and a Toggle widget. Bind each Toggle's initial value to a boolean field on the user's Firestore document (e.g., notif_promotions). On the Toggle's On Changed action, first call the subscribeToTopic or unsubscribeFromTopic Custom Action depending on the new value, then update the matching Firestore field. This approach keeps server state and on-device subscriptions in sync, so you can also filter users in Cloud Functions using the Firestore field.

Create a Firebase Cloud Function (Node.js) that accepts a topic name and message payload and uses the Admin SDK to publish. Deploy it and call it from FlutterFlow using a Custom API Call or the Cloud Function action. In FlutterFlow go to Settings > Cloud Functions, add your deployed function, map the topic, title, and body parameters, and trigger it from an admin screen or a backend scheduled task. Only admin users should be able to trigger this — add a Firebase security rule or check custom claims inside the function.

1// functions/index.js
2const { onCall } = require('firebase-functions/v2/https');
3const { getMessaging } = require('firebase-admin/messaging');
4const { initializeApp } = require('firebase-admin/app');
5
6initializeApp();
7
8exports.sendToTopic = onCall(async (request) => {
9  const { topic, title, body, data } = request.data;
10  if (!request.auth?.token?.admin) {
11    throw new Error('Unauthorized');
12  }
13  const message = {
14    notification: { title, body },
15    data: data || {},
16    topic,
17  };
18  const response = await getMessaging().send(message);
19  return { messageId: response };
20});

For dynamic segments not suitable for topics (e.g., 'users who purchased in the last 30 days'), use a Cloud Function that queries Firestore, collects up to 500 FCM tokens per batch, and calls sendEachForMulticast. Create a scheduled Cloud Function or an onCall function with an admin guard. Query your users collection with the desired filter, map results to their fcmToken fields, chunk into arrays of 500, and send. Log failed tokens and remove them from Firestore to keep your token list clean.

1// functions/sendToSegment.js
2const { onCall } = require('firebase-functions/v2/https');
3const { getMessaging } = require('firebase-admin/messaging');
4const { getFirestore } = require('firebase-admin/firestore');
5
6exports.sendToSegment = onCall(async (request) => {
7  const { filter, title, body } = request.data;
8  const db = getFirestore();
9  let query = db.collection('users');
10  if (filter.plan) query = query.where('plan', '==', filter.plan);
11  if (filter.region) query = query.where('region', '==', filter.region);
12  const snap = await query.get();
13  const tokens = snap.docs
14    .map(d => d.data().fcmToken)
15    .filter(Boolean);
16  const chunkSize = 500;
17  let sent = 0;
18  for (let i = 0; i < tokens.length; i += chunkSize) {
19    const chunk = tokens.slice(i, i + chunkSize);
20    const result = await getMessaging().sendEachForMulticast({
21      tokens: chunk,
22      notification: { title, body },
23    });
24    sent += result.successCount;
25  }
26  return { sent };
27});