JSON to TypeScript
JSON to TypeScript is a free online tool that converts JSON data into TypeScript interface definitions in real time. Paste JSON on the left and typed interfaces appear instantly on the right — nested objects are automatically split into separate interfaces, saving you from writing types by hand.
The conversion runs entirely in your browser, so your JSON never leaves your device. It's free with no registration, ideal for frontend developers generating type definitions from real API responses to speed up TypeScript development.
How to Use
- Paste or type your JSON into the left editor
- TypeScript interfaces are generated automatically on the right
- If the JSON is invalid, fix it using the error message shown
- Copy the generated interfaces into your .ts files
FAQ
Is the JSON to TypeScript converter free?
Yes, it's completely free with no usage limits and no account needed.
Is my JSON sent to a server?
No. Everything runs locally in your browser, so sensitive API data never leaves your machine.
How are nested JSON structures handled?
Nested objects are extracted into separate interfaces that reference each other, and arrays are typed based on their element structure, so the output is ready to use as-is.
Why generate interfaces from JSON instead of writing them manually?
Hand-writing types for large or deeply nested API responses is slow and error-prone. Generating them from real JSON guarantees every field is covered with an accurate type.