JSON Schema Generator

The JSON Schema Generator is a free browser-based utility that automatically infers and generates a JSON Schema (Draft 2020-12) from any sample JSON data. When designing REST API contracts, documenting data structures shared between frontend and backend teams, or setting up runtime validation with libraries like Ajv or Zod, having an accurate JSON Schema is essential.

However, manually writing a schema for deeply nested JSON objects is tedious and error-prone—typos in property names and incorrect type definitions are common pitfalls. This tool eliminates that burden entirely: simply paste your actual JSON response or sample data into the input area.

The tool recursively infers every field's type (string, number, boolean, null, object, array), builds nested properties definitions for objects, defines items schemas for arrays, and marks all discovered keys as required. For heterogeneous arrays containing mixed types, the tool intelligently generates anyOf schemas to capture all possible item types.

Advanced format detection automatically recognizes common patterns such as email addresses, ISO date-time strings, UUIDs, and URIs, and appends format metadata (format: "email", format: "date-time", etc.) for seamless integration with validation frameworks and tools like Ajv.

The output conforms to JSON Schema Draft 2020-12 with the $schema metadata automatically included. Because all processing runs entirely within your browser's JavaScript engine, sensitive API responses, internal configuration files, and proprietary data structures are never transmitted to any external server. The generated schema can be copied to the clipboard with a single click—choose between compact or pretty-printed output—and used directly in OpenAPI specifications, validation pipelines, or documentation systems.