JSON to TypeScript Converter

What this tool does

The JSON to TypeScript Converter turns raw JSON into ready to use TypeScript interfaces. It uses a two-pane editor: paste an object or array on the left and it generates a typed interface called Root on the right the moment you type, plus separate interfaces for any nested objects it finds. There is no Convert button, and if the JSON is invalid a clear inline message shows what to fix. When the interfaces look right, you can copy them or download them as a .ts file. It is built for frontend and backend developers who work with API responses, config files, or sample payloads and want strong typing without writing every interface by hand.

How to use it

1. Paste or type your JSON into the left pane, or click Load example to drop in a sample object with quoted keys and matching brackets.
2. The TypeScript interfaces appear in the right pane instantly as you type, so there is nothing to click to generate them.
3. If the JSON is invalid, an inline error explains the problem, such as a trailing comma or a single quote. Fix the input and the interfaces reappear right away.
4. Use Copy to grab the result, or Download to save it as a .ts file, then drop it straight into your project. Clear empties both panes when you want to start over.

A quick example

Paste this:

{"id":1,"name":"Ada","address":{"city":"Paris"}}

You get an interface Root with id typed as number and name typed as string, plus a nested Address interface holding city as string. Each nested object becomes its own interface, which keeps the output readable and easy to reuse across your codebase. A common gotcha is trailing commas or single quotes, which are valid in JavaScript but not in JSON, so clean those up first if the converter reports a problem.

This tool runs entirely in your browser. It is private, free, and needs no sign-up.