Installability criteria and the web app manifest, member by member

What: The concrete bar a web app must clear to be offered for installation, and the manifest members that control identity, launch, appearance and integration once installed.

Why: Agents routinely ship a manifest missing id or scope, forget the 512 px icon, or assume Lighthouse will grade "PWA-ness" (that category was removed). Getting the manifest right is cheap and it decides the launcher icon, the first-paint background, whether the URL bar leaks in, and whether a later change of start URL is treated as a different app.

Use when: creating or auditing any installable web app.

Do not confuse "installable" with "app-like": offline, native feel and performance are separate work (pwa-app-shell-and-offline-fallback, pwa-standalone-display-and-safe-areas).

1. Chromium installability (Chrome, Edge, Samsung Internet): served over HTTPS (or localhost/loopback — file:// never qualifies); a manifest linked from every page that can be a launch target (<link rel="manifest" href="/manifest.webmanifest">); manifest contains name or short_name, icons with at least 192×192 and 512×512, start_url, display and/or display_override, and prefer_related_applications absent or false. A service worker is not required for menu install (dropped in Chrome 108 mobile / 112 desktop) — but it is required for offline, caching and push, so treat it as mandatory in practice. Chrome also lets users install any site as an app without a manifest; the manifest is what earns promotion.
2. Safari: macOS 14+ "Add to Dock" and iOS/iPadOS 16.4+ Share → Add to Home Screen work with or without a manifest; from Safari/iOS 26 every added site opens as a web app by default ("Open as Web App" toggle) and there are zero installability requirements. No beforeinstallprompt exists on iOS (pwa-ios-safari-limits).
3. Firefox: desktop does not install web apps; Firefox for Android offers add-to-home-screen — verify current behaviour.
4. Manifest members that matter:
   • identity/launch: id (set it explicitly so start_url can change later), name, short_name, description, start_url, scope (out-of-scope navigations reveal the URL bar).
   • appearance: display (standalone | fullscreen | minimal-ui | browser), display_override (ordered list tried first — how you opt into window-controls-overlay or tabbed with a fallback), orientation, theme_color, background_color (painted before CSS loads — match your app background to avoid a flash).
   • icons: icons[] with sizes, type, purpose (any, maskable, monochrome) — see pwa-icons-maskable-and-screenshots.
   • store-like: screenshots (enables the richer install sheet), categories, shortcuts (long-press icon menu).
   • deeper integration (Chromium-leaning): launch_handler, file_handlers, protocol_handlers, share_target.
5. Minimal correct manifest:

{
  "id": "/?source=pwa",
  "name": "Field Notes", "short_name": "Field Notes",
  "description": "Capture and review notes, online or offline.",
  "start_url": "/?source=pwa", "scope": "/",
  "display": "standalone",
  "display_override": ["standalone", "minimal-ui", "browser"],
  "background_color": "#0b0f14", "theme_color": "#0b0f14",
  "icons": [
    { "src": "/icons/icon-192.png", "sizes": "192x192", "type": "image/png", "purpose": "any" },
    { "src": "/icons/icon-512.png", "sizes": "512x512", "type": "image/png", "purpose": "any" },
    { "src": "/icons/icon-maskable-512.png", "sizes": "512x512", "type": "image/png", "purpose": "maskable" }
  ]
}

6. Do not rely on a Lighthouse PWA score — the category was removed; audit against the checklist below instead.

• Page served over HTTPS; manifest linked from every launchable page.
• id, name/short_name, start_url, scope, display set explicitly.
• 192 and 512 any icons plus a 512 maskable icon resolve (no 404).
• background_color matches the app background — no first-paint flash on launch.
• Service worker registered (for offline, not for the install gate).
• Install is offered as an enhancement, never a gate (impossible to prompt on iOS).
• Chrome DevTools → Application → Manifest shows no warnings; installed app opens without the URL bar.

Sources:

• https://developer.mozilla.org/en-US/docs/Web/Progressive_web_apps/Guides/Making_PWAs_installable
• https://developer.mozilla.org/en-US/docs/Web/Progressive_web_apps/Manifest/Reference
• https://developer.chrome.com/blog/update-install-criteria
• https://webkit.org/blog/17333/webkit-features-in-safari-26-0/
• https://w3c.github.io/manifest/

• Exactly which signal triggers Chrome's automatic install prompt is fast-moving; the menu-install criteria above are stable.
• display_override, launch_handler, file_handlers, protocol_handlers and share_target are Chromium-leaning and marked experimental on MDN; feature-detect and never make them load-bearing.
• Safari ignores most manifest members beyond icons, colours and display; iOS splash screens come from background_color and the icon.
• A manifest cannot make a site feel like an app; it only makes it installable.
• Values verified 2026-09-26: all 1 numeric values in this item were checked (1 against platform documentation) and confirmed; no corrections were needed.