JSON to TypeScript Converter

Typing out interface definitions by hand for an API response or config file is tedious and easy to get subtly wrong. This tool reads a JSON sample and generates matching TypeScript interface definitions automatically — inferring strings, numbers, booleans, arrays, and nested objects, and splitting nested structures into their own named interfaces rather than one giant inline type.

For example, {"name": "Alice", "address": {"city": "NYC"}} generates:

interface Address {
  city: string;
}

interface Root {
  name: string;
  address: Address;
}

Paste your JSON into the input box on the left, set the Interface name you want for the top-level type, and click Convert. The generated TypeScript appears in the output box on the right, with any parse errors shown below.