JSON to TypeScript Converter

What this does

Paste an API response or config file and get TypeScript interfaces that describe it. Nested objects become their own named interfaces, arrays become T[], and a field that is missing from some objects in an array is marked optional with?. A top-level array works too: the element objects are merged into one interface.

Example

{
  "id": 42,
  "name": "Ada",
  "verified": true,
  "tags": [
    "admin",
    "dev"
  ],
  "orders": [
    {
      "sku": "A1",
      "qty": 2
    },
    {
      "sku": "B2",
      "qty": 1,
      "note": "gift"
    }
  ]
}

export interface Root {
    id:       number;
    name:     string;
    verified: boolean;
    tags:     string[];
    orders:   Order[];
}

export interface Order {
    sku:   string;
    qty:   number;
    note?: string;
}

Options

• Type name: the name of the root interface (default Root).
• Types only: on by default, which gives plain declarations. Turn it off to also get a Convert class with runtime-checked JSON parsing helpers.
• Type aliases switches interface Foo {} totype Foo = {}; Readonly addsreadonly to every property.
• Detect dates and UUIDs types ISO 8601 strings as Date. Turn it off to keep them as string, which matches what JSON.parseactually returns.

Things to know

The types are inferred from the sample you give, so they are only as complete as that sample: a field that is always present in your sample will be required, and a field that isnull everywhere becomes null. Feed it several representative objects in an array to get realistic optional fields. Mixed arrays becomeArray<number | string>. If you need validation at runtime, use theJSON to Zod converter instead.

Privacy

Generation runs in a Web Worker in your browser. The JSON is never uploaded.