JSON to TypeScript Interface Generator
Paste JSON and get clean TypeScript interfaces instantly — nested objects become named interfaces, arrays of objects are merged with optional properties detected, unions inferred. 100% client-side.
About JSON to TypeScript Interface Generator
JSON to TypeScript Interface Generator converts any JSON payload into clean TypeScript interfaces instantly — nested objects become named interfaces, arrays of objects are merged with optional properties detected automatically, and mixed-type arrays come out as unions. Paste an API response, copy the types, done.
How to use JSON to TypeScript Interface Generator
- 1Paste or type your input into the box above — a sample is pre-filled so you can try it instantly.
- 2Set any options on offer (mode, key, format) to match what you need.
- 3The result appears the moment you type — no button to press, no waiting.
- 4Click Copy to grab the output — JSON to TypeScript Interface Generator keeps everything on your device.
Why use JSON to TypeScript Interface Generator?
- ✓Typing a third-party API response without writing interfaces by hand
- ✓Generating types for config files, fixtures and mock data
- ✓Bootstrapping types when migrating a JavaScript codebase to TypeScript
- ✓100% free with no sign-up, no watermark and no usage limits
- ✓Runs entirely in your browser — your text and keys are never uploaded, stored or logged
- ✓Works offline once loaded, with instant results and one-click copy
Frequently asked questions
How are arrays of objects typed?+
Every element is merged into one interface: a property present in only some elements becomes optional (giftWrap?: boolean) and a property whose type varies becomes a union. That mirrors how real API lists behave and saves you from runtime surprises the first sample object would hide.
Is my JSON uploaded anywhere?+
No — parsing and generation run entirely in your browser, so production API responses and payloads with real customer data stay on your machine. That is a meaningful difference from converter sites that round-trip your JSON through their server.
Is it free to use?+
Yes — completely free with no sign-up, no account and no usage limits. There is no paywall, so you can encode, decode and convert as much as you like.
Is my data private and secure?+
Yes. This tool runs entirely in your browser using client-side JavaScript — your input is never uploaded to a server, stored or logged. Once the page has loaded you can use it offline, which makes it safe for tokens, keys and confidential data.
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