JSON to TypeScript Converter

Paste a representative API response and the converter writes the matching TypeScript declarations. Each nested object becomes its own named interface, named after its key: an address object becomes Address, and the items of an orders array become Order. The root name is yours to choose.

Arrays are inspected element by element and the shapes are merged. If one object in an array has a field that another lacks, the field becomes optional (gift?: boolean). If an array mixes types you get a union such as (number | string)[]. Empty arrays become unknown[], because nothing can be inferred from them, and a null value is typed null.

Choose interface or type declarations, add or drop export, and mark every property readonly for immutable data. Keys that are not valid identifiers, such as full-name, are quoted automatically.

Input:

{"id": 42, "email": null, "roles": ["admin"],
 "orders": [{"sku": "A1", "qty": 2}, {"sku": "B2", "qty": 1, "gift": true}]}

Output:

export interface Root {
  id: number;
  email: null;
  roles: string[];
  orders: Order[];
}

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

The second order has a gift field the first lacks, so it is optional in the merged type.

• A sample is only evidence. A field that is null in your sample is probably string | null in reality, so adjust it by hand.
• Include several array items, including unusual ones, so optional fields and unions are discovered.
• Numbers are always number; there is no integer type in TypeScript.
• Generated types describe the shape only. Validate untrusted data at runtime, for example with the JSON Schema validator.