Definition

screenshots (manifest field)

Short definition

screenshots is a manifest array such as [{"src": "/shots/home.png", "sizes": "1080x1920", "type": "image/png", "form_factor": "narrow"}] used to render a richer install UI with app previews, similar to a Play Store listing, instead of the plain one-line install banner.

Reviewed July 23, 2026

form_factor: "narrow" targets mobile-shaped screenshots and "wide" targets desktop-shaped ones; supplying both lets Chromium choose the appropriate set depending on the device that is installing.

The richer install dialog with screenshots is currently a Chromium/Android feature and requires at least one narrow screenshot; without any screenshots the browser falls back to the standard mini-infobar or install icon.

Screenshots are not resized automatically to fit — the spec recommends real device-resolution captures rather than scaled-down thumbnails, since blurry screenshots are a common review complaint in installability audits.

This field has no effect on iOS, where installation always goes through the manual Safari share-sheet flow with no preview gallery.

Related terms

shortcuts (manifest field)

shortcuts is a manifest array of up to (practically) four entries, each with name, url and optional icons, that appear when a user long-presses the installed app icon on Android or right-clicks it on Windows/ChromeOS. Example: {"name": "New order", "url": "/orders/new", "icons": [{"src": "/shortcut-new.png", "sizes": "96x96"}]}.

Web App Manifest

A Web App Manifest is a JSON file (usually manifest.webmanifest) that declares your app's name, icons, start URL, theme colour and display mode. The browser reads it to render the install prompt and the home-screen icon.

Lighthouse PWA audit

The Lighthouse PWA audit, run from Chrome DevTools' Lighthouse panel or the lighthouse CLI, checks a page against Chromium's installability criteria — valid manifest fields, icon sizes, registered service worker, HTTPS — and flags exactly which checks pass or fail, rather than giving a single opaque score for the category.

id (manifest field)

id is a manifest field, for example "id": "/app-v1", used as the app's permanent identifier for the OS install registry. Unlike start_url, id is not meant to change; if it is omitted, the browser derives an identity from start_url instead, which means later changing start_url can register as a brand-new app.

orientation (manifest field)

orientation is a manifest field, e.g. "orientation": "portrait-primary", that requests a fixed screen orientation for the installed app. Accepted values include any, natural, landscape, portrait, portrait-primary, portrait-secondary, landscape-primary and landscape-secondary.

categories (manifest field)

categories is an optional manifest array, for example "categories": ["shopping", "business"], drawn loosely from a W3C-maintained list of common app-store category names. It has no effect on install eligibility or on-page behaviour and is purely metadata consumed by platforms that list PWAs alongside native apps.