JSON to TypeScript
Paste a JSON object or array and instantly get a matching TypeScript interface — nested objects become their own named interfaces, and arrays infer their element type.
About the JSON to TypeScript
Hand-writing a TypeScript interface for an API response is tedious and drifts out of sync the moment the API changes. Generating it from a real sample response instead gets you a working starting point in seconds — this is the same idea popularized by tools like quicktype, applied to a single flat conversion.
Because a single JSON sample only shows one shape, the generated interface reflects exactly what was in that sample — a field that's sometimes a string and sometimes null in other responses won't be inferred as optional unless your sample happens to include both cases. Treat the output as a strong starting draft, not a substitute for a real API schema.
How to use it
- 1Paste a JSON object or array — a real API response works well.
- 2Read the generated interface(s).
- 3Copy the result into your codebase.
Features
- Infers string, number, boolean, null and array types
- Generates a separate named interface for each nested object
- Handles arrays of objects and arrays of primitives
- Configurable root interface name
Frequently asked questions
How does it decide field types?
Each field's type is inferred directly from the JSON value in your sample — strings become string, numbers become number, and nested objects become their own separate interface.
What happens with an array of objects?
The element type is inferred from the objects in the array and generated as its own named interface, referenced as Type[] in the parent.
Will it mark fields as optional?
Only based on what's in your sample — since a single sample can't show every possible shape of the data, review the output against your actual API docs if some fields are sometimes absent.
Is my JSON uploaded?
No. Generation happens entirely in your browser; nothing is sent to a server.