What is a progressive web app (PWA)?

A PWA is a website that behaves like a native app. It can be installed on your home screen, work offline, send push notifications, and load instantly — all without going through an app store.

Technically, a PWA is a regular website enhanced with three things: a Service Worker (a script that runs in the background for caching and offline support), a Web App Manifest (a JSON file that tells the browser how to display the app when installed), and HTTPS (required for Service Worker security).

PWAs are ideal when you want app-like behavior without the cost and complexity of native development. Building a PWA adds about 10-20% to website development cost. Building a native app adds 200-400%.

Examples of successful PWAs: Twitter Lite (65% increase in pages per session), Starbucks (2× daily active users compared to native), Pinterest (60% increase in engagement). These companies built PWAs not to replace their native apps, but to reach users who won't download apps.

Limitations on iOS: Apple's Safari has limited PWA support compared to Chrome. Push notifications on iOS PWAs were only added in 2023 and still have restrictions. If your primary audience is iPhone users, test carefully before committing.