Validate PWA manifest.json files for required fields, icon sizes, and Web App Manifest specification compliance.
Manifest.json Validator examines a Web App Manifest and reports whether it is valid JSON and whether its members, required values, and declared icons satisfy the validator's manifest checks. It is useful before linking a manifest from an HTML page or while investigating installation problems. The frequent surprise is that valid JSON is only the first gate: a document can parse cleanly while still containing missing fields, incorrect value types, unusable URLs, or icon declarations that do not meet the expected rules.
The validation has two distinct questions. First, the submission must be a JSON object, so quoted names, commas, arrays, and value types must follow JSON syntax. After parsing, the manifest-specific pass can examine recognized members and the validator's required-field expectations. If parsing fails, checks involving name, start_url, display, icons, and their value types cannot be meaningfully completed.
An icons member is an array of image resource objects. Within each entry, src names the resource, sizes is a string containing dimension tokens such as 192x192 or the keyword any, and type can identify the media type. The validator can assess those declarations for its icon-size rules, but a well-formed descriptor should not be confused with proof that the deployed image is reachable and correct.
No. The result concerns the manifest text and the checks reported for it. Installation also depends on how the page links the manifest, whether referenced URLs work from the served manifest's location, the security context, browser policy, and other application conditions. Test the deployed site in each target browser after fixing the document-level findings.
Manifest icon sizes are declarations, not image dimensions discovered from the JSON alone. The sizes value is a JSON string, even when it contains several tokens; it is not an array of numbers. Use tokens such as 192x192 or 512x512, separated by spaces when appropriate, or any for a scalable resource. Each icon also needs a string src value.
The behavioral notes were checked against the browser implementation. Standards and primary references below define the relevant format, formula, or platform behavior.
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