FCM Server

A Node.js server for sending Firebase Cloud Messaging (FCM) push notifications using the Firebase Admin SDK.

This server refers to "Trusted Environment" and "Backend" in the above images, respectively

Features

• Send notifications to single devices
• Send notifications to multiple devices
• Send notifications to topics
• Subscribe/unsubscribe devices to/from topics
• Send data-only messages (silent notifications)
• Send multiple data messages to multiple devices
• Send multiple data messages with configurable intervals
• Input validation and error handling
• CORS and security headers
• Health check endpoint

Setup

Prerequisites

• Node.js (v14 or higher)
• Firebase project with FCM enabled
• Firebase service account key

Installation

1. Clone or download this project

2. Install dependencies:

   npm install

3. Set up Firebase configuration:

   Option 1: Environment Variables

   • Copy .env.example to .env
   • Fill in your Firebase project details:

     FIREBASE_PROJECT_ID=your-project-id
     FIREBASE_CLIENT_EMAIL=your-client-email
     FIREBASE_PRIVATE_KEY=your-private-key
     

   Option 2: Service Account Key File

   • Download your Firebase service account key JSON file
   • Place it in the config/ directory
   • Set the path in .env:

     FIREBASE_SERVICE_ACCOUNT_PATH=./config/serviceAccountKey.json
     

Getting Firebase Credentials

1. Go to Firebase Console
2. Select your project
3. Go to Project Settings → Service Accounts
4. Click "Generate New Private Key"
5. Download the JSON file or copy the credentials

Usage

Start the server

Development:

npm run dev

Production:

npm start

The server will start on port 3000 by default.

API Endpoints

Health Check

GET /health

Send Notification to Single Device

POST /api/notifications/send-to-device
Content-Type: application/json

{
  "token": "FCM_REGISTRATION_TOKEN",
  "notification": {
    "title": "Hello World",
    "body": "This is a test notification",
    "imageUrl": "https://example.com/image.jpg" // optional
  },
  "data": { // optional
    "key1": "value1",
    "key2": "value2"
  }
}

Send Notification to Multiple Devices

POST /api/notifications/send-to-multiple
Content-Type: application/json

{
  "tokens": ["TOKEN1", "TOKEN2", "TOKEN3"],
  "notification": {
    "title": "Hello World",
    "body": "This is a test notification"
  },
  "data": {
    "key1": "value1"
  }
}

Send Notification to Topic

POST /api/notifications/send-to-topic
Content-Type: application/json

{
  "topic": "news",
  "notification": {
    "title": "Breaking News",
    "body": "Important news update"
  },
  "data": {
    "category": "news"
  }
}

Subscribe to Topic

POST /api/notifications/subscribe-to-topic
Content-Type: application/json

{
  "tokens": ["TOKEN1", "TOKEN2"],
  "topic": "news"
}

Unsubscribe from Topic

POST /api/notifications/unsubscribe-from-topic
Content-Type: application/json

{
  "tokens": ["TOKEN1", "TOKEN2"],
  "topic": "news"
}

Send Data-Only Message

POST /api/notifications/send-data-message
Content-Type: application/json

{
  "token": "FCM_REGISTRATION_TOKEN",
  "data": {
    "action": "sync",
    "timestamp": "2023-01-01T00:00:00Z"
  }
}

Send Multiple Data Messages

POST /api/notifications/send-multiple-data-messages
Content-Type: application/json

{
  "tokens": ["TOKEN1", "TOKEN2", "TOKEN3"],
  "data": {
    "action": "bulk_sync",
    "timestamp": "2023-01-01T00:00:00Z"
  },
  "count": 5
}

Send Multiple Data Messages with Interval

POST /api/notifications/send-multiple-data-messages-with-interval
Content-Type: application/json

{
  "tokens": ["TOKEN1", "TOKEN2", "TOKEN3"],
  "data": {
    "action": "scheduled_sync",
    "timestamp": "2023-01-01T00:00:00Z"
  },
  "count": 10,
  "interval": 5000
}

Response Format

Success Response

{
  "success": true,
  "messageId": "MESSAGE_ID",
  "message": "Notification sent successfully"
}

Error Response

{
  "success": false,
  "error": "Error message"
}

Error Handling

The server handles various FCM errors:

• Invalid registration tokens
• Unregistered tokens
• Invalid payloads
• Network errors

Security

• Helmet.js for security headers
• CORS enabled
• Input validation
• Request size limits

Environment Variables

Variable	Description	Required
PORT	Server port (default: 3000)	No
NODE_ENV	Environment (development/production)	No
FIREBASE_PROJECT_ID	Firebase project ID	Yes*
FIREBASE_CLIENT_EMAIL	Firebase client email	Yes*
FIREBASE_PRIVATE_KEY	Firebase private key	Yes*
FIREBASE_SERVICE_ACCOUNT_PATH	Path to service account key file	Yes*

*Either environment variables OR service account key file is required.

Testing

You can test the endpoints using curl, Postman, or any HTTP client:

# Test health endpoint
curl http://localhost:3000/health

# Test notification
curl -X POST http://localhost:3000/api/notifications/send-to-device \
  -H "Content-Type: application/json" \
  -d '{
    "token": "YOUR_FCM_TOKEN",
    "notification": {
      "title": "Test",
      "body": "Hello from FCM Server"
    }
  }'

# Test multiple data messages
curl -X POST http://localhost:3000/api/notifications/send-multiple-data-messages \
  -H "Content-Type: application/json" \
  -d '{
    "tokens": ["YOUR_FCM_TOKEN"],
    "data": {
      "action": "test"
    },
    "count": 3
  }'

License

MIT