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Android FCM Setup

a0 uses Firebase Cloud Messaging (FCM v1) to deliver push notifications to Android devices. You need two files from Firebase:
FilePurpose
google-services.jsonRegisters your Android app with Firebase. Injected into the APK at build time.
Firebase service account keyPrivate key used by a0’s servers to send notifications via the FCM v1 API.

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Step 1: Create a Firebase project

If you already have a Firebase project for your app, skip to Step 2.
  1. Open the Firebase Console
  2. Click Add project and follow the setup wizard
Creating a new Firebase project

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Step 2: Download google-services.json

This file contains your Firebase project’s public configuration and is required for your Android app to connect to Firebase.
  1. In the Firebase Console, open Project settings (gear icon)
  2. Under Your apps, select your Android app (or click Add app → Android if you haven’t added one yet)
  3. Enter your Android package name — this should match the bundle identifier used in your a0 project
  4. Click Download google-services.json
Downloading google-services.json from Firebase Console
This file contains public-facing identifiers and is safe to commit to your repository. It does not contain any private keys.

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Step 3: Create a Firebase service account key

The service account key is a private JSON file that authorizes a0’s servers to send push notifications on your behalf via the FCM v1 API.
  1. In the Firebase Console, open Project settings → Service accounts
  2. Make sure Firebase Admin SDK is selected
Firebase Service accounts settings
  1. Click Generate New Private Key
  2. Confirm by clicking Generate Key — a JSON file will download
Generating a new private key
Store this file securely. It contains a private key that grants access to send notifications to your app. Do not commit it to your repository.

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Using an existing service account

If you already have a Google Cloud service account and want to reuse it for FCM:
  1. Open the IAM Admin page in Google Cloud Console
  2. Find the service account you want to use and click the pencil icon to Edit Principal
IAM Admin page in Google Cloud Console
  1. Click Add Role and select Firebase Cloud Messaging API Admin
Adding Firebase Messaging API Admin role
  1. Click Save
  2. Download a new JSON key for this service account if you don’t already have one

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Step 4: Upload to a0

  1. Open your project in a0
  2. Go to Project Settings → Build Settings → Android Credentials
  3. Upload your google-services.json file
  4. Upload your Firebase service account key file
  5. Build a new custom APK — the credentials will be included automatically
Both files will show a Configured badge once uploaded. You can replace or delete them at any time.
After uploading new credentials, you need to create a new APK build for the changes to take effect. Existing builds will continue using the credentials they were built with.