JSON → TypeScript

Paste an API response, get interfaces you can actually keep.

Root type name

JSONvalid JSON

{
  "id": "ord_9f2c",
  "createdAt": "2026-10-14T09:31:02Z",
  "paid": true,
  "total": 128.5,
  "refundedAt": null,
  "customer": {
    "name": "Matvejs",
    "email": "hello@example.com",
    "address": { "city": "Riga", "zip": "LV-1010" }
  },
  "items": [
    { "sku": "sku_a", "qty": 2, "price": 39.0 },
    { "sku": "sku_b", "qty": 1, "price": 50.5, "discount": 10 }
  ]
}

TypeScript4 interfaces

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

interface Customer {
    name: string;
    email: string;
    address: Address;
}

interface Item {
    sku: string;
    qty: number;
    price: number;
    discount?: number;
}

interface Response {
    id: string;
    createdAt: string;
    paid: boolean;
    total: number;
    refundedAt: null;
    customer: Customer;
    items: Item[];
}

How it works

The JSON is parsed, walked once, and every value is reduced to a type. Objects get merged so optional keys are marked with a question mark, arrays are unified into one item type, and a value that is sometimes null produces a union with null. Nothing is inferred from the key name — only from the data, which is why the result stays honest.

Built withTypeScript · Vue 3