Automatically generate a JSON Schema definition from sample JSON data. Infers types, required fields, and constraints.
JSON Schema will appear here...Enter a sample JSON document.
A JSON Schema is generated automatically.
Copy and customize the generated schema.
Use the JSON Schema Generator when you need to create API contracts, validate request/response payloads, or document your data structures. It saves hours of manually writing schemas by automatically inferring types from sample data. Backend developers use it to generate validation schemas for Express, FastAPI, or Spring Boot endpoints from existing JSON examples.
The tool generates Draft-07 compatible schemas by default, which is the most widely supported version across validators and tooling. Draft-07 supports advanced features like conditional schemas, if/then/else keywords, and content encoding. The generated schema can be used directly with popular validation libraries like Ajv or jsonschema.
Yes, all fields present in the sample JSON data are automatically marked as required in the generated schema. You can then review and adjust which fields should truly be required versus optional for your use case. Providing multiple sample documents helps the tool infer optionality more accurately.
Yes, the tool infers array item types by analyzing elements in the sample data. For arrays with consistent object structures, it generates a detailed items schema with full property definitions. Mixed-type arrays are handled with oneOf schemas to capture all possible item formats.