Developer tool

JSON to TypeScript

Turn JSON payloads into TypeScript interfaces or type aliases. Nested objects, arrays, and optional fields are inferred in your browser.

JSON lines

Current input

Types

Generated

Root

object

JSON shape

Private by defaultNested interfacesOptional fields

Type workspace

Paste JSON, get TypeScript

What & how guide

JSONTypeScript

export interface User {
  id: number;
  name: string;
  email: string;
  active: boolean;
  plan: null;
  roles: string[];
  profile: Profile;
  orders: Order[];
}

export interface Profile {
  city: string;
  timezone: string;
}

export interface Order {
  id: number;
  total: number;
  paid: boolean;
  coupon?: string;
}

Ready to generate types.

GuideGenerate types in three steps3 steps

Paste JSON

Drop in an API payload, fixture, or config object. Nothing is uploaded.

Tune the output

Choose a root name, interfaces or type aliases, and whether types are exported.

Copy TypeScript

Review inferred nested types and optional fields, then copy the result into your project.

More toolsRelated tools

JSON to TypeScript Guide

Learn how inference, optional fields, and nested interfaces work.

JSON Viewer

Format and inspect JSON before you turn it into types.

JavaScript Formatter

Beautify the script that will consume the generated types.

FAQFrequently asked questions

Does this send my JSON to a server?

No. Parsing and type generation run locally in your browser.

How are optional fields decided?

When an array contains objects with different keys, missing keys become optional. Null values are typed as null and unioned with the other observed types.

Can it convert a JSON array at the root?

Yes. A root array becomes a type alias such as Root = User[], plus interfaces for nested objects.

Does it generate runtime validators?

No. It only emits TypeScript types. Use it for models, API clients, and fixtures, then add a validator if you need runtime checks.

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