JSON to TypeScript

Convert JSON to TypeScript interfaces online — nested objects become named interfaces, optional fields detected across arrays. Free, no upload.

JSON input

{
  "id": 42,
  "name": "Ada",
  "roles": ["admin", "editor"],
  "address": { "city": "London", "zip": null }
}

TypeScript interfaces

interface Root {
  id: number;
  name: string;
  roles: string[];
  address: Addres;
}

interface Addres {
  city: string;
  zip: null;
}

About JSON to TypeScript

Paste any JSON object and get clean TypeScript interfaces: nested objects become separately named interfaces, arrays are type-merged, and fields missing in some array items are marked optional.

Numbers become number, true/false become boolean, nulls become null|any unions where needed. Conversion runs entirely in your browser.