JSON to TypeScript

Generate TypeScript types from JSON

Writing interfaces by hand for a large API response is slow and easy to get wrong. Paste a real response here and you get a set of export interface declarations you can drop into your project: one for the root object and one for each nested object, named after its key.

Arrays of objects are merged, so a field that appears in only some items is marked optional with ?, and a field that holds different types becomes a union such as string | number. Tick the option to get type aliases instead of interfaces.

Example

JSON input (root name set to User):

{
  "id": 42,
  "name": "Sara Khan",
  "roles": ["admin", "editor"],
  "address": { "city": "Lahore", "zip": "54000" },
  "orders": [
    { "id": 1, "total": 19.99 },
    { "id": 2, "total": 5, "coupon": "WELCOME" }
  ],
  "deletedAt": null
}

TypeScript output:

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

export interface Order {
  id: number;
  total: number;
  coupon?: string;
}

export interface User {
  id: number;
  name: string;
  roles: string[];
  address: Address;
  orders: Order[];
  deletedAt: null;
}

Note how coupon became optional because only one order has it, and orders got its own Order interface.