pushNotifications

Push notifications are messages sent from a server to a user’s device or browser to provide timely information or updates, even when the target application is not actively in use. They can trigger alerts, sounds, or badge indicators and may include a data payload that the app uses to fetch content or perform actions.

Implementation involves three main parts: the client app or website, a push service, and the application server. The client subscribes to a platform’s push service to obtain a unique device token. When a notification is needed, the application server sends a request to the push service with the token and payload. The push service authenticates the sender and delivers the message to the device, where the operating system or browser presents it to the user. Web push uses a Service Worker and the Push API to receive messages in the background and display native-style notifications.

Examples of platforms include Apple Push Notification Service (APNs) for iOS and macOS, Firebase Cloud Messaging (FCM) for Android, and the Web Push protocol used by modern browsers. Web push typically encrypts data with VAPID keys and a transport layer, while mobile push uses platform-specific channels.

Permissions and privacy are important: users must opt in to receive notifications, and data minimization and secure handling are advised. Users can usually revoke permission or mute notifications. Payloads should avoid sensitive data and respect user preferences, and developers should implement reasonable TTL and retry logic.

Limitations include dependency on network connectivity, potential latency, platform-imposed limits, and battery or data usage concerns. Push notifications complement in-app messaging by enabling outreach even when apps are closed, but can contribute to notification fatigue if overused.