JSON to TypeScript Converter

Q: 3. What happens if a property is null?

If a property's value is null, the generator will mark the property as optional (with a ?) and assign it the type any, since the exact type cannot be inferred.

100% Free · Client-Side

Convert JSON objects into well-formatted TypeScript interfaces or types instantly. Works entirely offline in your browser for total privacy.

JSON Input

Root Name:

export interface RootObject {
  id: number;
  name: string;
  username: string;
  email: string;
  address: Address;
  phone: string;
  website: string;
  company: Company;
}

export interface Company {
  name: string;
  catchPhrase: string;
  bs: string;
}

export interface Address {
  street: string;
  suite: string;
  city: string;
  zipcode: string;
  geo: Geo;
}

export interface Geo {
  lat: string;
  lng: string;
}

What is the JSON to TypeScript Converter?

The JSON to TypeScript Converter is a developer tool that automatically generates strongly-typed TypeScript interfaces or type aliases from raw JSON data. By pasting API responses or configuration payloads, you instantly receive precise types—saving time and preventing manual typing errors.

Features

Complete Privacy: Powered entirely in your browser. Your JSON data is never transmitted to any server.
Deep Array Merging: Scans objects inside arrays and intelligently merges properties to provide comprehensive, unified interfaces.
Interface vs Type Aliases: Easily toggle between generating interface definitions and type aliases.
Null safety: Automatically infers null values as optional properties.

Frequently Asked Questions

1. Is my JSON data sent to any server?

No. The conversion happens entirely locally in your web browser. Your JSON data never leaves your device, ensuring complete privacy.

2. How does the converter handle arrays of objects?

It merges all objects within the array to ensure the resulting TypeScript interface includes every possible property found across the array's items.

3. What happens if a property is null?

If a property's value is null, the generator will mark the property as optional (with a ?) and assign it the type any, since the exact type cannot be inferred.

4. What is the difference between Interface and Type alias?

Both are valid ways to define custom types in TypeScript. Interfaces are generally preferred for object shapes as they are easier to extend, while Type aliases can represent primitives, unions, and tuples. You can toggle between both formats in the settings.