The Firebase Admin SDK allows you to integrate your own backend services with Firebase Cloud Messaging (FCM). The Admin FCM API handles authenticating with Firebase servers while facilitating sending messages and managing topic subscriptions.
You can use the Firebase Admin SDK to send Firebase Cloud Messaging messages to end-user devices. Specifically, you can send messages to individual devices, named topics, or condition statements that match one or more topics. The Admin Node.js SDK provides additional methods for sending messages to device groups.
The Admin FCM API enables constructing message payloads tailored to different target platforms (Android, iOS and Web). If a message payload contains configuration options for multiple platforms, the FCM service customizes the message for each platform when delivering.
Managing topic subscriptions
The Firebase Admin SDK provides an API for subscribing and unsubscribing devices to and from FCM topics. These operations can subscribe or unsubscribe up to 1000 device registration tokens at a time.