Useful Commons

Free browser tool

Check JSON against a schema

Check an instance against a bounded JSON Schema subset and get paths for every detected problem.

Your file stays on this device. No upload, account or tracking.

Use the tool

Paste text or choose a UTF-8 file. Up to 600,000 characters per document, 5,000 array items, 1,000 object fields and 100 reported errors.

Supports type, properties, required, additionalProperties, items, size limits, number limits, enum, const and date, date-time, email or UUID formats. Remote references and regular expressions are not accepted.

What this tool does

Validate JSON against a safe, bounded JSON Schema subset without uploading either document.

Limits and safe use

Up to 600,000 characters per document, 5,000 array items, 1,000 object fields and 100 reported errors. Keep the original file and review the output before using it elsewhere. This tool does not certify an import, infer missing meaning or send data to a model.