# Progressive Web App (PWA)

> A Progressive Web App is a website that behaves like an installed app: it can be added to the home screen, opens in its own window without a browser address…

Source: https://northerngo.com/glossary/progressive-web-app/
Language: en
Updated: 2026-08-28

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**A Progressive Web App is a website that behaves like an installed app: it can be added to the home screen, opens in its own window without a browser address bar, and can keep working without a connection if it ships a service worker. It is distributed by URL, not through an app store.**

### What actually makes an app a PWA

Three technical pieces, all of which the browser checks before it offers to install anything:

- **HTTPS.** Required, with no exceptions on a real domain.
- **A [web app manifest](/glossary/web-app-manifest/)** — a small JSON file that gives the operating system a name, an icon and a display mode, so the app opens in its own window instead of a browser tab.
- **A [service worker](/glossary/service-worker/)** — a script the browser keeps installed and consults before it goes to the network.

Meet all three and Chrome, Edge and Android offer "Install app"; on iOS the user adds it from the Share menu. The result is an icon on the home screen and an app that launches without an address bar — but it is still a website. It updates the moment you deploy, there is no store review, and it can be shared as a link.

### Where PWAs win, and where they genuinely lose

They win on distribution and on iteration cost. One codebase serves phone, tablet and desktop, there is no app store commission, and a bug fix reaches every user on next launch instead of after a review queue.

They lose on anything that depends on deep operating system integration. iOS support for push notifications and background sync is limited and arrived late, Safari can evict stored data after a few weeks without use, and some hardware APIs — Bluetooth, NFC, precise background location — are unavailable or inconsistent across browsers. If those are core to the product, a PWA is the wrong container.

### The misconception: installable does not mean offline

This is the part people get wrong. A PWA that can be installed to the home screen is not automatically an offline app. Installability comes from the manifest; offline behaviour comes entirely from what the service worker chooses to cache. An installed PWA with no caching strategy shows the same blank screen in airplane mode that the website did.

Offline also has to be earned while online, because the first visit is what downloads and stores the files. Anything live — a database read, a login, a cloud AI call — still fails without a connection, and [designing an app around that](/resources/offline-first-web-apps-pwa/) is a deliberate choice rather than a setting you switch on.

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