Firebase provider

The Firebase provider wraps Firebase Cloud Messaging (FCM) for push. Add the peer dependencies:

yarn add firebase @capacitor/push-notifications

Configure

FirebaseConfig is a union — pass a raw config object or an existing Firebase app.

Raw config

import { notifications } from 'notification-kit';

await notifications.init({
  provider: 'firebase',
  config: {
    apiKey: '...',
    authDomain: '...',
    projectId: '...',
    storageBucket: '...',
    messagingSenderId: '...',
    appId: '...',
    measurementId: '...',   // optional
    vapidKey: '...',        // required for web push
  },
});

Existing Firebase app

If your app already created a Firebase instance, reuse it:

import { initializeApp } from 'firebase/app';

const app = initializeApp(firebaseOptions);

await notifications.init({
  provider: 'firebase',
  config: { app, vapidKey: '...' },
});

Or via the quick-start helper:

import { quickStart } from 'notification-kit';
await quickStart.initFirebaseWithApp(app, vapidKey);

What the provider does

Method	Behaviour
requestPermission()	Requests notification permission and registers for FCM.
getToken()	Returns the FCM registration token.
deleteToken()	Deletes the current FCM token.
onMessage	Foreground message delivery → surfaces as notificationReceived.
onTokenRefresh	Token rotation → surfaces as tokenRefreshed.

Server-side only operations (important)

These deliberately throw on the client because FCM requires admin credentials for them:

• subscribe(topic) / unsubscribe(topic) — FCM topic management is an Admin SDK / IID API operation. The provider throws a descriptive error: send the device token from getToken() to your backend and subscribe it there.
• sendNotification(payload) — client-side sending is not supported; it throws. Send from your backend with the Admin SDK.
• getSubscriptions() — FCM does not expose a device's topic subscriptions to the client; it returns [] so callers can treat "unknown" as "none". Track subscriptions in your backend if you need an authoritative list.

// Server-side
import admin from 'firebase-admin';
await admin.messaging().subscribeToTopic([token], 'news');
await admin.messaging().send({ token, notification: { title, body } });

Web push

Web push needs a VAPID key and a service worker (firebase-messaging-sw.js). See Web setup.

Banned native plugins

Do not add @capacitor-firebase/crashlytics or @capacitor-firebase/performance alongside this provider — they require extra Gradle/Console wiring and are unrelated to messaging. Use Sentry for errors if you need crash reporting.