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JSON to TypeScript Interface Generator

Generate a TypeScript interface from a JSON sample (merges keys, infers types, handles nesting).

Automatically generates a TypeScript interface from a sample JSON object. Saves you the time of hand-typing type declarations for API data.

How to use JSON → TypeScript

  1. Paste a JSON object that represents your data.
  2. The tool infers the types and generates a TypeScript interface.
  3. Copy the interface into your project.

Frequently asked questions

Does it detect arrays and nested objects?

Yes, the tool generates nested interfaces that match the JSON structure.

How are null/optional fields handled?

Fields with a null value get a broader inferred type; you should review these and add a ? for fields that aren't required.

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🔒 JSON to TypeScript Interface Generator runs entirely in your browser — the data you enter is not sent to any server. Free, no sign-up required. See145 free dev tools more.