App Push notifications feel simple on the surface: “Something happened — tell the user.”

But under the hood, iOS, macOS, and Android all rely on a centralized push infrastructure, and that design choice has deep implications for privacy, decentralization, battery life, and system architecture.

Push notifications require a central server because mobile operating systems do not allow apps to stay permanently connected in the background.

Instead, iOS and Android maintain a single, system-level connection to their own push services (APNs and FCM). Your server sends the notification to Apple or Google, and their infrastructure delivers it to the device efficiently and securely.

Without this centralized intermediary, apps would need to keep constant network connections open, which would drain battery, increase data usage, and weaken the platform’s security model.