JSON to TypeScript Interface Generator

Convert JSON objects to TypeScript interfaces instantly. Supports nested objects and arrays.

interface User {
  id: number;
  name: string;
  email: string;
  roles: string[];
  active: boolean;
  score: number;
  address: null;
}

interface Root {
  user: User;
}

✅ Generates interface declarations from a JSON object.

✅ Supports nested objects, arrays, booleans, numbers, strings and null.

✅ All processing happens in your browser — no data is sent anywhere.

Frequently Asked Questions

What does JSON to TypeScript do?

It converts a JSON object into TypeScript interface declarations, inferring types automatically so you can use them in your TypeScript projects.

Does it support nested objects?

Yes. Each nested object generates its own interface, which is referenced from the parent interface.

Is my JSON data sent to a server?

No. The conversion runs entirely in your browser using JavaScript — your data never leaves your device.

Does it handle arrays?

Yes. Arrays infer the type of the first element and produce a typed array (e.g. string[], number[], or a custom interface[]).

Why Use TypeScript Interfaces for API Data?

When you consume a REST API in TypeScript and type the response asany, you lose all type safety. Generating interfaces from a real API response gives you:

  • IDE autocompletion for every property.
  • Compile-time errors when you access a field that doesn't exist.
  • Refactor safety — rename a field and TypeScript finds every reference.
  • Living documentation that stays in sync with the data shape.

Example: JSON → TypeScript Interfaces

Input JSON

{
  "id": 1,
  "name": "Alice",
  "active": true,
  "score": 9.5,
  "tags": ["admin", "beta"],
  "address": {
    "street": "123 Main St",
    "city": "Springfield"
  }
}

Generated TypeScript

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

interface Root {
  id: number;
  name: string;
  active: boolean;
  score: number;
  tags: string[];
  address: Address;
}

TypeScript Type Generation Ecosystem

  • quicktype — generates types from JSON, JSON Schema, or GraphQL for TypeScript, Python, Go, Rust, and more.
  • zod — define a schema in TypeScript code and infer the type from it; great for runtime validation + type safety.
  • openapi-typescript — generates TypeScript types from OpenAPI 3 spec files, keeping client and server in sync.
  • json-schema-to-ts — converts a JSON Schema to a TypeScript type at compile time via template literal types.