JSON to TypeScript

Paste JSON and get TypeScript interface or type definitions generated recursively. Handles nested objects, arrays, union types from mixed arrays, and null values. Saves the tedious step of writing types by hand for API responses and config objects.

Root name:

Use type alias

JSON Input

TypeScript Output

interface Address {
  street: string;
  city: string;
  zip: null;
}

interface User {
  id: number;
  name: string;
  email: string;
  roles: (string)[];
  address: Address;
  active: boolean;
  score: number;
}

interface Root {
  user: User;
}

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What it generates

Nested objects become separate named interfaces/types, referenced by the parent.
Arrays are typed as T[]. Mixed-type arrays produce union types like (string | number)[].
null values are typed as null.
Keys with special characters are automatically quoted.

Interface vs type alias

Both produce equivalent results for object shapes. interface supports declaration merging; type is more flexible for union and intersection types. Toggle the switch to choose.

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