Data & Conversion
JSON → TypeScript / Python
Generate TypeScript interfaces or Python dataclasses from JSON.
JSON to TypeScript Interface & Python Dataclass Generator
Converting JSON data into typed structures is a common task when working with APIs, configuration files, or database schemas. This tool takes any valid JSON input and generates a matching TypeScript interface or Python dataclass — complete with proper type inference for strings, numbers, booleans, arrays, and nested objects. It handles arrays of mixed types by inferring union types in TypeScript and Union types in Python. Nested objects are automatically extracted into separate named types for clean, readable code. Simply paste your JSON, choose your target language, and click Generate. The output is ready to paste directly into your codebase. Everything runs in your browser — no data is sent to any server.
Frequently Asked Questions
How does the type inference work?
The generator analyzes each JSON value's JavaScript type: strings become string / str, numbers become number / float (or int for whole numbers in Python), booleans become boolean / bool, and null values produce optional types. Arrays are typed by inspecting all elements — if all elements share the same type, the array is typed uniformly; if they differ, a union type is used.
Does it handle deeply nested JSON?
Yes. Nested objects are extracted into their own named interfaces (TypeScript) or dataclasses (Python). The naming convention uses the parent key as the type name (e.g., a key called "address" becomes interface Address). Deeply nested structures produce multiple types, all properly cross-referenced.
Can I use the generated code in production?
The generated types are a starting point. They're syntactically correct but may need refinement — for example, you might want to rename generic type names, add validation decorators (in Python), or mark certain fields as optional based on your domain knowledge.
Is my JSON sent to a server?
No. All type generation happens entirely in your browser using JavaScript. Your JSON data never leaves your device.