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To send push notifications to Android devices through the Google Play Store, OneSignal requires Firebase Cloud Messaging (FCM) credentials. This guide walks you through generating the required Service Account JSON file and uploading it to your OneSignal app settings. For technical background, see Google’s Service Account documentation.
This guide is for developers integrating OneSignal with an Android mobile app distributed via the Google Play Store.

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Requirements

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Setup

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1. Create or open your Firebase Project

Go to the Firebase console.
  • If you don’t have a project yet, click Add project and complete the setup.
  • If you already have a project, select it.

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2. Enable Firebase Cloud Messaging API v1

1

Go to Project Settings

In Firebase, click the gear icon next to Project Overview > Project settings.
2

Go to Cloud Messaging

Go to the Cloud Messaging tab.If Firebase Cloud Messaging API (V1) is disabled, click the 3-dot menu > Open in Cloud Console.
In the Google Cloud Console, click Enable. Wait a few minutes for the change to reflect in Firebase.

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3. Generate a Service Account JSON file

1

Return to Project Settings > Service Accounts

At the bottom, click Generate new private key.
2

Confirm and generate key

Confirm by clicking Generate key in the popup.
3

Save the file

Save the .json file in a secure location. You will need it shortly.
Required Service Account permissions:
  • cloudmessaging.messages.create
  • firebase.projects.get
These are included by default. If you’re using a custom Service Account, ensure it has:
  • roles/firebasemessaging.admin
  • roles/firebase.viewer

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4. Upload your credentials to OneSignal

1

Go to Android platform settings

In your OneSignal dashboard, go to: Settings > Push & In-App > Push Platforms > Google Android (FCM).Click Activate.
2

Upload your credentials

Upload the .json file under Service Account JSON by clicking Choose file.
If prompted, select Firebase Cloud Messaging API (V1) from the dropdown.To verify you’re using the correct Firebase project, match the Sender ID in Firebase (Cloud Messaging > Sender ID) with the one shown in your OneSignal settings.
3

Save and continue

4

Choose your SDK

Select the SDK you are using and click Save & Continue.
5

Add the OneSignal App ID to your code

Continue following the Mobile SDK setup and add this OneSignal App ID to your code.
You’ve successfully connected your OneSignal app to Firebase Cloud Messaging (V1).Next, complete Mobile SDK setup or go to Mobile push setup for platform-specific instructions.

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FAQ

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Error: “This configuration is for a different Firebase Project…”

This error occurs when the uploaded JSON file belongs to a different Firebase project (i.e., different Sender ID). Solution: Use the original Firebase project’s JSON file. If unavailable, contact [email protected] with your App ID. Switching projects resets push tokens—your users must reopen the app to get push again.

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Can I change my Sender ID?

No. The Sender ID is locked once your app surpasses 100 Android users to prevent accidental invalidation of push tokens. If necessary, contact [email protected] with your App ID for assistance.

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Do I need to update my code when switching to FCM V1?

No app or SDK changes are required—this is a dashboard-only update.

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What is the deadline for switching to FCM v1?

Google began deprecating legacy FCM APIs in July 2024. Migration is strongly recommended. See Google’s announcement.

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Why don’t I see a Sender ID in OneSignal?

If your Firebase server key looks like AIz..., you’re likely using an outdated Google Cloud Messaging (GCM) setup. Create a new Firebase project and upload a Service Account JSON file.

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How can I check which apps are still using the Legacy API?

Use the View apps API and check for:
  • "gcm_key" → using Legacy, needs update
  • "fcm_v1_service_account_json" → using V1 ✅
  • Neither → app does not use Android push