This project implements a real-time push notification system using Firebase Cloud Messaging (FCM) integrated with Node.js, Express, and MongoDB. It allows you to register user devices, manage FCM tokens, send notifications in bulk or to topics, and auto-clean invalid tokens for better performance and reliability.
- 📱 Register user device tokens (with phone, email, username)
- 🚀 Send single or bulk push notifications via FCM
- 🔔 Subscribe and send messages to FCM topics
- 🧼 Auto-clean invalid tokens from MongoDB
- 🗃️ Manage FCM tokens per user in MongoDB