100% local — your data never leaves your browser

JSON to TypeScript Converter — Free Online Tool

Convert JSON to TypeScript interfaces instantly in your browser. Free, private and offline-friendly: your data never leaves your device.

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JSON input

TypeScript output

Why convert JSON to TypeScript?

Typing your API responses by hand is tedious and error-prone. Paste a sample JSON payload above and get ready-to-use TypeScript interfaces in milliseconds, including nested objects and arrays.

How it works

The converter parses your JSON locally and infers the most precise TypeScript type for each field: string, number, boolean, null, arrays and nested interfaces. Mixed arrays are typed as unions.

Frequently asked questions

Is my JSON data uploaded to a server?
No. The conversion runs entirely in your browser with JavaScript. Nothing is sent over the network, which makes the tool safe for sensitive data.
How are nested objects handled?
Each nested object becomes its own TypeScript interface, named after its key in PascalCase, and referenced from the parent interface.
Is this tool free to use?
Yes, the converter is completely free, with no account, no ads and no usage limits.