JSON to TypeScript & Types

Turn sample JSON into TypeScript, Go, Rust, Python, Swift & more type definitions — locally.

Convert sample JSON to TypeScript interfaces — plus Go, Rust, Python & Swift types. Generate an interface from JSON free and in your browser; nothing is…

About JSON to TypeScript & Types

JSON to TypeScript & Types is a free, browser-based code generator that turns a sample JSON object into ready-to-paste type definitions for eight languages: TypeScript, Go, Rust, Python, Java, C#, Kotlin, and Swift. It infers field names, value types, nested objects, and arrays from your example and renders just the type declarations (no extra serialization helpers) using the quicktype engine (Apache-2.0). Everything runs locally in your browser — your JSON is parsed and analyzed in the tab and never uploaded, with no account required.

How to use JSON to TypeScript & Types

  1. Paste or type a sample JSON object into the 'JSON input' box (a worked example is pre-filled to start from).
  2. Set the 'Top-level type name' (defaults to 'Root') — this becomes the name of the root interface/struct/class.
  3. Pick your target language from the dropdown: TypeScript, Go, Rust, Python, Java, C#, Kotlin, or Swift.
  4. Click 'Generate types' — your JSON is validated locally first, and any syntax error is shown inline.
  5. Read the generated type definitions in the output panel and use the Copy button to grab them.
  6. Switch the language and regenerate any time to get the same shape in another language.

Frequently asked questions

Is my JSON uploaded to a server?
No. Your JSON is validated, parsed, and converted to types entirely in your browser tab — nothing is ever uploaded, and the data never leaves your device.
Is it free and do I need an account?
Yes, it's completely free with no signup, login, or limits.
Which languages can I generate types for?
Eight: TypeScript, Go, Rust, Python, Java, C#, Kotlin, and Swift. Pick the target from the Language dropdown before generating.
What engine does it use under the hood?
It uses quicktype-core (Apache-2.0), loaded on demand the first time you generate, so the page stays lightweight until you actually need it.
Does it generate full classes with parsing code, or just the types?
Just the type definitions — it runs quicktype in 'just-types' mode, so you get clean interfaces, structs, or classes without extra serialization or converter boilerplate.
What happens if my JSON is invalid?
The tool validates the JSON locally before generating and shows an inline error message describing the parse problem, so nothing is generated until the input is valid JSON.

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