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Web App Manifest Validator

Network

Validate a web app manifest.json against the W3C Web App Manifest spec's installability requirements: name/short_name, start_url, display mode, and an icons array covering a 512x512 and a maskable icon

Paste a web app manifest.json and see exactly which installability requirements it's missing before a browser or app store rejects it. It checks the fields Chrome and other browsers actually require for an install prompt: at least one of name or short_name, an absolute or relative start_url, a recognized display mode, and a non-empty icons array. It also flags softer issues as warnings, like a missing 512x512 icon needed for splash screens or a missing maskable icon that Android needs to avoid cropping your logo badly. This is a structural spec check, not a live installability audit like Lighthouse runs against a deployed site.

pwamanifestvalidatorjsonweb-app

How to use Web App Manifest Validator

  • 1.Paste the contents of your manifest.json into the input box.
  • 2.Review the issues list: errors mean the manifest fails the spec's installability requirements, warnings are recommended fields or icon sizes worth adding.
  • 3.Check the icons panel to confirm every icon's src, sizes, and purpose match what you intended.

Frequently asked questions

Does this fetch my manifest from a live URL?
No, you paste the raw JSON directly. It doesn't make any network requests, so it works for manifests that aren't publicly deployed yet.
What counts as an error versus a warning?
Errors are things that break installability outright: missing name and short_name, a missing start_url, an invalid display value, or a missing/empty icons array. Warnings are recommended-but-not-required fields like background_color, or icon coverage gaps like no 512x512 or maskable icon.
Does it check whether my icon files actually exist or load?
No, this is a structural validator only. It checks the JSON against the manifest spec, not whether each icon src actually resolves to a real image.
Does it replicate Lighthouse's PWA installability audit exactly?
No, Lighthouse also checks things like whether a service worker is registered and whether the site is served over HTTPS. This tool only validates the manifest.json document itself.

Use via API, SDK, or MCP

cURL# Free: 1,000 req/day · Pro: 10,000 req/day
curl -X POST https://api.utilix.tech/v1/tools/manifest-validator \
  -H "Authorization: Bearer utx_live_..." \
  -H "Content-Type: application/json" \
  -d '{"manifest":"{\"name\":\"My App\",\"short_name\":\"App\",\"start_url\":\"/\",\"display\":\"standalone\",\"icons\":[{\"src\":\"/icon-512.png\",\"sizes\":\"512x512\",\"purpose\":\"any maskable\"}]}"}'

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