Manifest screenshots and richer install UI

In one line: screenshots is an array of promotional images shown in richer install dialogs — on Chrome for Android these appear as a scrollable carousel above the “Add to Home Screen” button, giving users a preview of the app before they install it. Without screenshots, browsers show a minimal install prompt with only the icon and name.

Syntax

{
  "screenshots": [
    {
      "src": "/screenshots/home-mobile.png",
      "sizes": "390x844",
      "type": "image/png",
      "form_factor": "narrow",
      "label": "Home screen showing today's tasks"
    },
    {
      "src": "/screenshots/dashboard-desktop.png",
      "sizes": "1280x800",
      "type": "image/png",
      "form_factor": "wide",
      "label": "Dashboard with analytics overview"
    }
  ]
}

Each screenshot object:

Property	Required	Description
src	Yes	URL of the image, relative to the manifest.
sizes	Yes	WIDTHxHEIGHT in CSS pixels.
type	Recommended	MIME type: image/png, image/jpeg, image/webp.
form_factor	Recommended	"narrow" (mobile portrait) or "wide" (desktop/tablet landscape).
label	Recommended	Accessible description of the screenshot content.

form_factor

form_factor tells the browser which screenshots to show on which device class:

• "narrow" — shown on mobile (portrait-dominant) install prompts.
• "wide" — shown on desktop/tablet (landscape-dominant) install prompts.
• Omitted — browser may show the screenshot on any form factor.

Providing separate screenshots for each form_factor ensures mobile users see mobile-shaped previews and desktop users see desktop-shaped previews, which increases install conversion.

Image requirements and recommendations

• Minimum dimension: 320 px on either side.
• Maximum dimension: 3840 px on either side.
• Aspect ratio: the ratio of sizes dimensions must match the actual image. Mismatches cause the browser to skip the screenshot.
• Recommended for "narrow": match a common phone resolution such as 390 × 844 or 375 × 812.
• Recommended for "wide": 1280 × 800 or 1920 × 1080.
• At least one screenshot is recommended to unlock the “richer install UI” in Chrome for Android.

Richer install UI (Chrome for Android)

When a manifest includes at least one screenshot with a matching form_factor or no form_factor, Chrome for Android upgrades the install bottom sheet to a full-height modal with:

• The app icon and name.
• A scrollable carousel of screenshots.
• The install button.

Without screenshots, Chrome uses a compact bottom sheet. The richer UI consistently improves install rates in A/B tests.

Practical checklist

• At least one screenshot is present to unlock the richer install dialog on Android.
• Screenshots use the correct aspect ratio matching the sizes value.
• form_factor is set to "narrow" for mobile shots and "wide" for desktop shots.
• Each screenshot has a descriptive label for accessibility.
• Images are optimised (compressed PNG or WebP) — these are promotional assets loaded at install time, not at runtime.
• Screenshots show real app UI, not placeholder or stock imagery.