What a Progressive Web App (PWA) is
A Progressive Web App is a website built with modern web technologies so it feels and behaves like a mobile app. It’s still delivered from the web — no separate binary to download and no app-store submission required — but it can be installed to a user’s home screen, run offline, and use features such as push notifications. The idea is to combine the reach of the web with many of the capabilities people expect from native apps.
How PWAs work (the essentials)
- Secure origin: PWAs must be served over HTTPS. That protects users and lets browsers enable powerful features.
- Service workers: This is the piece of code that runs in the background and intercepts network requests. It enables reliable loading (by serving cached resources when the network is slow or unavailable), background tasks and handling push messages. Service workers are central to offline behaviour and fast repeat loads.
- Web App Manifest: A small JSON file that tells the browser how the app should appear and launch. Typical fields include name, short_name, start_url and display (commonly set to standalone or fullscreen). The manifest also references icon images used for the home-screen shortcut.
- Icons: A PWA should provide at least one suitable icon for home-screen use. Historically designers used sizes such as 144×144 pixels; modern practice is to provide multiple sizes so the system can pick the best one.
What PWAs offer users and businesses
- Quick launch and reliability: With a properly configured service worker, a PWA can load instantly on repeat visits and continue to function when the network is flaky or absent.
- Installable to home screen: Rather than forcing a user to visit an app store, many PWAs present an “add to home screen” option, giving a familiar app-like shortcut.
- Push notifications: Web push lets sites re-engage users with timely messages, even when the site isn’t open. Support varies by platform and browser, but it’s a powerful re-engagement tool when available.
- App-like performance: Modern browsers support smooth animations, efficient scrolling and responsive layouts, so a well-built PWA can feel as fluid as a native app.
- Security and responsiveness: Delivered over HTTPS, PWAs protect data in transit. They’re built to adapt to phones, tablets and laptops, so the same codebase can serve many devices.
- Easier deployment and updates: Because a PWA is published like any other website, updates are delivered centrally — users don’t need to install updates through an app store.
What to bear in mind
PWAs are not a silver bullet. Feature support differs between browsers and operating systems, so some platform-specific behaviours may still require native development. Also, not every use case needs offline caching or push notifications; sometimes a responsive website is enough. For many projects, though, a PWA provides a pragmatic middle ground — faster to ship than two separate native apps, while delivering a more app-like experience than a traditional mobile website.
If you’re evaluating ways to reach mobile users, a PWA is worth considering: it’s a web-first approach that can provide many of the conveniences people expect from native apps, without the overhead of native app stores and separate binaries.