FCM HTTP v1 Setup for Firebase Projects

Google retired the FCM Legacy HTTP API (server key + fcm.googleapis.com/fcm/send). New and existing projects should migrate to HTTP v1, which offers better security, error reporting, and platform-specific message options.

Enable Firebase Cloud Messaging API

In Google Cloud Console, open APIs & Services → Library and enable "Firebase Cloud Messaging API". In Firebase Console → Project settings → Cloud Messaging, confirm your sender ID and app configurations are present.

Service account vs user OAuth token

Production backends typically use a service account JSON key and generate tokens with google-auth-library. For manual testing, a user OAuth token from gcloud auth print-access-token is sufficient. TestFCM accepts the short-lived user token for quick tests.

Grant the account the Firebase Cloud Messaging Admin role or a custom role with cloudmessaging.messages.create permission.

Message structure overview

HTTP v1 POST body wraps the payload in a message object: token (single device), topic, or condition. notification carries title and body for display notifications. data carries custom key-value pairs (all strings).

{
  "message": {
    "token": "DEVICE_TOKEN",
    "notification": {
      "title": "Hello",
      "body": "Test from HTTP v1"
    },
    "data": {
      "screen": "home"
    }
  }
}

Why TestFCM uses a server proxy

Browsers block direct calls to fcm.googleapis.com due to CORS. TestFCM's /api/send-fcm endpoint forwards your payload server-side so you can test from the web UI without running your own backend locally.