Are nested objects turned into separate interfaces?

Yes, each nested object gets its own named interface based on its key.

Can I generate type aliases instead of interfaces?

Yes, toggle 'Use type aliases' in the options bar.

How are null fields handled?

You can mark fields that were null as optional with the corresponding switch.

JSON to TypeScript Interface

Infer TypeScript interfaces or type aliases from JSON data.

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Root type name

Use type aliases

Mark null fields optional

JSON Input

TypeScript Output

interface RootObject {
  id: number;
  name: string;
  active: boolean;
  tags: string[];
  address: Address;
  score?: null;
}

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

About the JSON to TypeScript Interface

Paste a JSON object or array and instantly generate matching TypeScript interfaces or type aliases, with nested objects and arrays turned into their own named types.

Examples

Simple object

{ "id": 1, "name": "Ada" }

Output

interface RootObject {
  id: number;
  name: string;
}

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Frequently asked questions

Version 1.0.0 · Updated 2026-08-06 · Runs entirely in your browser