JSON Schema Generator
Generate JSON Schema, TypeScript interfaces, C# models, and Python dataclasses from any JSON sample. Instant output, copy with one click.
Paste a representative API response and generate a solid first pass for TypeScript, JSON Schema, C#, Python, or Kotlin.
Paste a JSON sample to generate types
Supports TypeScript, C#, Python, Kotlin, and JSON Schema
Why generate types from JSON?
When integrating with an API or data source, you often receive a JSON payload first and need to create typed models in your application. Manually writing TypeScript interfaces, C# classes, or Python dataclasses for complex nested JSON is tedious and error-prone. This tool generates a solid starting point instantly — paste a real API response and get production-ready type definitions.
Typical workflow
- 1Capture a real API response or test fixture
- 2Paste it into the input panel
- 3Select your target language (TypeScript, C#, Python, JSON Schema)
- 4Copy the generated type and paste into your project
- 5Review optional fields and nullable types — adjust where needed
JSON Schema vs TypeScript vs generated models
JSON Schema is language-agnostic and machine-readable — ideal for validation, OpenAPI documentation, and sharing schema definitions across services. TypeScript interfaces give you compile-time type safety in Node.js and browser applications. C# models and Python dataclasses are ready for deserialization from JSON in backend services.
Related Tools
Frequently Asked Questions
JSON Schema is a vocabulary for annotating and validating JSON documents. A schema describes the expected structure, types, and constraints of a JSON document. It's used for API documentation (OpenAPI), form validation, data validation in pipelines, and code generation.
The generator infers types from a single sample. It assumes all fields are required, uses the most specific type for each value, and does not detect nullable fields unless the value is explicitly null in the sample. For production use, review and adjust the generated schema — especially for optional fields and nullable types.
If a field is sometimes absent, remove it from the required array in the JSON Schema, or mark it as optional (?) in TypeScript. If a field can be null, add null to its type union. The generator infers from the sample you provide — if you want nullable handling, set the value to null in your sample.
Array types are inferred from the first element in the array. If you have an array of mixed types or an empty array, the inferred type will be generic (unknown[] in TypeScript, List<object> in C#). Provide a representative sample element to get a specific type.
Yes. The generator recursively traverses nested objects and arrays, generating the appropriate nested types in all output formats. Deeply nested structures produce nested interfaces in TypeScript and nested classes in C#.
The generated JSON Schema targets draft 2020-12 (the current specification). The $schema field is included for validation tools to correctly interpret the schema.