JSON Schema Generator
Paste any JSON and instantly generate a valid JSON Schema draft-07 document. Perfect for API validation, documentation, and contract testing — free, instant, no sign-up.
Also try the JSON Editor for a full-featured editing experience, or explore all JSON Tools in the complete toolkit.
What Is JSON Schema and Why Do You Need It?
JSON Schema is the standard way to describe the structure, types, and validation rules for a JSON document. It acts as a contract between a producer and consumer of data — if your API response or configuration file conforms to a schema, any client can validate it automatically without reading documentation or writing bespoke parsing logic. The JSON Schema Generator removes the most tedious step: writing that contract from scratch. Provide a representative sample, click generate, and you have a production-ready draft-07 schema in seconds. Use it with ajv in Node.js, jsonschema in Python, or any OpenAPI-compatible toolchain to catch malformed data at the edge before it reaches your application logic.
How to Generate JSON Schema from Any JSON Sample
The process is straightforward. Paste your JSON into the editor — it can be an API response, a config file, a database document, or any other JSON data. The tool traverses every key-value pair, infers the correct JSON Schema type for each field, and recursively handles nested objects and arrays of any depth. String fields get "type": "string", integer-valued numbers get "type": "integer", and boolean fields, null values, and floating-point numbers are all handled correctly. All keys present in the sample are included in the required array by default, giving you a strict schema you can relax as needed. The output is a clean, copyable, and downloadable .json file ready for immediate use.
Frequently Asked Questions
What is a JSON Schema?
A JSON Schema is a vocabulary that describes the structure and validation rules for JSON data. It defines the expected types, required properties, value constraints, and nested structure of a JSON document. JSON Schema is widely used for API contract testing, form validation, code generation, and documentation — tools like Postman, OpenAPI/Swagger, and ajv all rely on it.
How does the JSON Schema Generator work?
Paste any JSON sample into the editor and click Generate. The tool analyses every key and value in your document, infers the correct JSON Schema type for each field (string, number, integer, boolean, object, array, or null), marks all top-level keys as required by default, and recursively processes nested objects and arrays. The result is a valid JSON Schema draft-07 document you can copy or download immediately.
Which JSON Schema draft does this tool produce?
The generator produces JSON Schema draft-07, the most widely supported version. Draft-07 is compatible with ajv, Postman, OpenAPI 3.0, and the majority of validation libraries across JavaScript, Python, Java, Go, and .NET. If you need draft 2019-09 or draft 2020-12 features, the output is a solid starting point you can adjust manually.
Can the JSON Schema Generator handle arrays and nested objects?
Yes. Arrays are detected and their item types are inferred from the first element (or from a union of all element types if the array is mixed). Nested objects are recursively processed, producing nested "properties" blocks with their own "required" arrays. The tool correctly handles arrays of objects, arrays of primitives, and multi-level nesting of any depth.
How do I use the generated schema to validate JSON?
Copy the generated schema and use it with any JSON Schema validation library. In JavaScript/Node.js use ajv: install it with npm install ajv, import your schema, compile it with ajv.compile(schema), then call validate(data) to check any JSON object against your schema. In Python use jsonschema: pip install jsonschema, then call jsonschema.validate(data, schema). In Java use the everit-org/json-schema library. All of these accept standard draft-07 schemas like the ones this tool produces.