Best Free JSON Schema Validator
JSON Schema is the standard way to define the structure, types, and constraints for JSON data — used in API specifications (OpenAPI), configuration validation, and data pipeline contracts. devtoolkit.sh's JSON Schema Validator checks any JSON document against a JSON Schema definition and reports every validation error with the JSON path of the failing value and a clear description of the constraint that was violated. Paste your schema and your data, select the draft version (Draft 7, 2019-09, or 2020-12), and get instant validation results. All validation runs client-side with no data uploaded.
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Paste JSON data and a JSON Schema above to validate
FAQ
- Which JSON Schema drafts are supported?
- JSON Schema Draft 7, Draft 2019-09, and Draft 2020-12 are supported, covering all currently common schema versions used in APIs and tooling.
- What validation errors are reported?
- Type mismatches, missing required properties, pattern violations, enum constraint failures, minimum/maximum violations, and additional property violations are all reported with the exact JSON path of the failing value.
- Can I use this for OpenAPI schema validation?
- OpenAPI 3.x schemas are a superset of JSON Schema. The validator handles the core JSON Schema portions; OpenAPI-specific keywords like discriminator may not be evaluated.