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How to add a web app manifest

The manifest decides how your site looks when someone saves it to a home screen: without one they get a screenshot thumbnail and the raw URL as the label. A manifest link pointing at nothing is worse than none — the browser requests it on every first visit and gets an error.

What 13x checks

This is rule social.web-manifest in the public registry: Web app manifest and theme colour. It runs on every audit, against the pages we actually fetched, and its result is derived from the response rather than estimated.

Surface
Social & sharing
Score weight
3 of the readiness score
Scope
Runs on every audited page
Applies
To every site

Registry version 2026-07-30. Every rule is published, and the audit is deterministic — the same page produces the same finding every time.

The fix

The same text the audit hands you when this check fails on your own site.

Add a manifest so a saved-to-home-screen copy carries your icon and name rather than a screenshot and a URL.

html code
<link rel="manifest" href="/site.webmanifest" />
<meta name="theme-color" content="#0b0b12" />
json code
{
  "name": "example.com",
  "short_name": "example.com",
  "start_url": "/",
  "display": "standalone",
  "background_color": "#0b0b12",
  "theme_color": "#0b0b12",
  "icons": [
    { "src": "/icon-192.png", "sizes": "192x192", "type": "image/png" },
    { "src": "/icon-512.png", "sizes": "512x512", "type": "image/png" },
    {
      "src": "/icon-maskable.png",
      "sizes": "512x512",
      "type": "image/png",
      "purpose": "maskable"
    }
  ]
}

The maskable icon is the one people skip. Android crops icons to whatever shape the launcher uses; without a maskable variant your icon gets a white box around it or has its edges cut off. Keep the important content inside the middle 80% of the canvas.

short_name is what appears under the icon — keep it under about 12 characters or the launcher truncates it.

Framework-specific versions

Where the change differs enough to be worth writing out separately.

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