Progressive Web Apps (PWAs)

Overview

A Progressive Web App is a web application that uses modern browser capabilities to deliver a fast, reliable, and installable experience — even on unreliable networks. The three required pillars are:

1. HTTPS — Required in production for service workers to register (localhost is exempt for development).
2. Web App Manifest (manifest.json) — Makes the app installable and defines its appearance on device home screens.
3. Service Worker (sw.js) — A background script that intercepts network requests, manages caches, and enables offline functionality.

When to Use This Skill

• Use when the user wants their web app to work offline or on unreliable networks.
• Use when building a mobile-first web project where users should be able to install the app to their home screen.
• Use when the user asks about caching strategies, service workers, or improving web app performance and resilience.
• Use when the user mentions Workbox, web app manifests, background sync, or push notifications for the web.
• Use when the user asks "can my website be installed like an app?" or "how do I make my site work offline?" — even if they don't use the word PWA.

Deliverables Checklist