JSON to TypeScript - Generate TS Interfaces from JSON

About the JSON → TypeScript playground

The JSON → TypeScript tool inspects a JSON sample and generates matching TypeScript interfaces, inferring field types from the values it sees. Strings become string, numbers become number, booleans become boolean, arrays become typed arrays, and nested objects become their own interfaces. This saves the tedious, error-prone work of hand-writing types for API responses and gives you compile-time safety when consuming JSON data.

JSON is an untyped, text-based data format, while TypeScript adds a static type layer over JavaScript using interfaces and type aliases to describe the shape of data. An interface declares the expected keys and their types, letting the compiler catch mistakes like missing fields or wrong value types. Generating interfaces from a real JSON payload bridges the two so your code can treat dynamic data with confidence.

HostedJSON → TypeScript runtime

mainentry file

single fileworkspace

stdinprogram input

How it works

Write

The main file is the entry point for each run.

Give it input

Use the Input panel to pipe standard input to your program when it needs data.

Run

Run sends your code to a fresh hosted runtime and streams the result into the output panel.

Keep or share

Your draft stays in this browser, and Share creates a separate snapshot link.

External resources

typescriptlang.org— Official website
GitHub— Official spec repository

Input (JSON)

{
  "id": 1,
  "name": "Ada",
  "active": true,
  "roles": ["admin"]
}

Output (TypeScript)

interface Root {
  id: number;
  name: string;
  active: boolean;
  roles: string[];
}

Input (nested JSON)

{
  "user": {
    "id": 1,
    "email": "[email protected]"
  }
}

Output (TypeScript)

interface User {
  id: number;
  email: string;
}

interface Root {
  user: User;
}

Input (array of objects)

{
  "items": [
    { "id": 1, "qty": 2 }
  ]
}

Output (TypeScript)

interface Item {
  id: number;
  qty: number;
}

interface Root {
  items: Item[];
}

Input (mixed & null)

{
  "price": 9.99,
  "tags": ["a", "b"],
  "note": null
}

Output (TypeScript)

interface Root {
  price: number;
  tags: string[];
  note: null;
}

Input (deeply nested JSON)

{
  "order": {
    "id": 7,
    "customer": {
      "name": "Ada",
      "vip": true
    }
  }
}

Output (TypeScript)

interface Customer {
  name: string;
  vip: boolean;
}

interface Order {
  id: number;
  customer: Customer;
}

interface Root {
  order: Order;
}

Input (number & empty array)

{
  "count": 3,
  "ratios": [0.5, 1.5],
  "items": []
}

Output (TypeScript)

interface Root {
  count: number;
  ratios: number[];
  items: any[];
}

Input (array at top level)

[
  { "id": 1, "name": "Ada" },
  { "id": 2, "name": "Linus" }
]

Output (TypeScript)

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

type Root = RootItem[];

json

typescript

Output

TypeScript types

JSON → TypeScript

Write

Give it input

Run

Keep or share

Editing

Navigation

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