JSON Schema Generator & Validator

The JSON Schema Generator & Validator is a free online tool that automatically infers a JSON Schema from sample JSON data and validates JSON documents against schemas with detailed error reports. JSON Schema is the industry standard for describing and validating the structure of JSON data.

Manually writing JSON Schemas is time-consuming and error-prone. This tool analyzes your JSON data and generates a complete, standards-compliant schema including types, required properties, array item schemas, and nested object structures. You can then refine the generated schema and use it to validate other JSON documents.

It also works as a JSON Schema validator — paste a schema and a JSON document to check conformance, with clear error messages showing exactly where and why validation fails. Everything runs in your browser — no data is sent to any server.

1. Generate from JSON — Paste sample JSON data and the tool automatically infers a JSON Schema describing its structure, types, and required fields.
2. Edit the schema — Refine the generated schema — adjust types, add constraints (minLength, pattern, enum), mark fields optional, or add descriptions.
3. Validate JSON — Paste a JSON document and a schema to validate the document against the schema with detailed error paths and messages.
4. Copy the result — Copy the generated schema or validation report to your clipboard.

• Schema inference — Automatically generates JSON Schema from sample JSON data with correct types, required fields, and nested structures.
• Schema validation — Validates JSON documents against schemas with detailed error messages including JSON paths.
• Standards-compliant — Generates schemas following the JSON Schema specification (Draft 2020-12 / Draft-07).
• Nested object support — Handles deeply nested objects, arrays of objects, mixed arrays, and complex data structures.
• Syntax highlighting — Both JSON input and schema output are syntax-highlighted for easy reading.
• 100% client-side — No data is sent to any server. Safe for proprietary data structures.

• API contract definition — Generate schemas from API responses to define and enforce data contracts between services.
• Form validation — Use JSON Schema to validate form input on both client and server, ensuring consistent data quality.
• Configuration file validation — Define schemas for config files (settings.json, tsconfig.json) to catch errors before deployment.
• Documentation — Use generated schemas as documentation for your API's request and response formats.
• Code generation — JSON Schemas can be used to generate TypeScript types, validation code, and API documentation automatically.