Web App Manifest SEO Validator & PWA Install QA

How to use this validator

1. Open the manifest.json response from the deployed app, browser Network panel, source repo, or build artifact.
2. Paste the full JSON into the validator and run the check.
3. Fix missing name/short_name, start_url, display, icon src/sizes, or stale generated manifest output in your app config.
4. Review theme_color, background_color, icon sizes, maskable icons, and start_url routing as follow-up mobile install QA.
5. Re-run the validator, then verify installability in Chrome DevTools, Lighthouse, and target browsers/devices.

When to use it

• QA a PWA manifest before requesting browser installability tests, Lighthouse review, or app-like mobile install checks.
• Validate manifest.json generated by Next.js, Astro, WordPress, Shopify, Webflow, or a CMS/PWA plugin.
• Check staging manifests before deploying icon, display, theme color, background color, scope, or launch URL changes to production.
• Review client bug reports where an app installs with the wrong name, blank icon, poor splash color, or browser-style window.
• Pair manifest QA with favicon, Open Graph, JSON-LD logo, viewport, service worker, and mobile rendering checks during launch.
• Paste a manifest from a HAR/API debugging session after checking network logs with the HAR validator.

Common errors

• Missing both name and short_name, leaving installed-app labels blank or unreliable.
• Missing start_url after a framework or CMS manifest generator strips defaults.
• Using unsupported display values such as installed, app, pwa, or fullscreen-app.
• Icon objects that include src but omit sizes, or a manifest with no icons array at all.
• Missing 192x192 or 512x512 install icons, maskable icon purpose, theme_color, or background_color even though the minimum structure passes.
• Manifest start_url, scope, or icon paths that work locally but break under a base path, CDN rewrite, static export, or auth-protected preview.
• JSON syntax issues such as trailing commas, comments, single quotes, or copied JavaScript objects instead of JSON.

Limitations

• Structure validation only; it does not fetch icon files, verify image dimensions, or confirm MIME types.
• Does not verify that the manifest is linked from your HTML, served with the correct content type, or reachable from production.
• Does not validate service worker registration, offline behavior, maskable icon safe areas, screenshots, shortcuts, scope routing, categories, or related_applications deeply.
• Does not guarantee Chrome, Safari, Edge, Android, iOS, or app-store installability; browser-specific requirements still apply.
• A manifest can pass while production still fails if icon URLs 404, the manifest URL redirects, service workers are missing, or mobile browsers cache older metadata.

Tips

• Include at least 192x192 and 512x512 PNG icons for common install surfaces, even though this validator only checks src/sizes presence.
• Use standalone when you want an app-like window without browser chrome; use browser when you explicitly want a normal tab experience.
• Keep short_name concise enough for home-screen labels while using name for the fuller app title.
• Prefer root-relative start_url and icon paths when the manifest is served from the same origin as the app, and verify them under the production base path.
• Keep manifest icons visually aligned with favicon, apple-touch-icon, Open Graph image, and JSON-LD logo references.
• After this structural check passes, use browser DevTools to confirm the linked manifest URL, service worker, icon fetches, theme colors, display mode, and install prompt behavior.

Examples

Deep dive

FAQs

Is my manifest uploaded?

No. The manifest JSON is parsed and checked in your browser only. It is not sent, logged, stored, or shared.

Does this prove my PWA is installable?

No. It confirms basic manifest structure, but installability also depends on how the manifest is linked and served, browser requirements, icons that actually load, service worker behavior, and browser-specific rules.

Which fields does this manifest validator check?

It checks that name or short_name exists, start_url is present, display is one of fullscreen, standalone, minimal-ui, or browser, and icon entries include src and sizes.

Does it fetch or inspect icon images?

No. It counts and checks icon metadata only. Use browser DevTools or Lighthouse to verify that icon URLs load and have the expected dimensions, maskable safe areas, and MIME types.

Should manifest icons match my favicon and social assets?

They should feel like the same brand system. Keep manifest icons, favicon, apple-touch-icon, Open Graph image, and JSON-LD logo visually aligned while using sizes appropriate for each surface.

Why test the deployed manifest instead of source config?

Frameworks, CMS plugins, static exports, redirects, and deployment rewrites can change the final manifest response. Browser install prompts use the deployed JSON, not your source component.

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