JSON to TypeScript Converter
Turn a JSON sample into TypeScript interfaces automatically — infers types, nested objects and arrays.
interface Root {
id: number;
name: string;
active: boolean;
roles: string[];
profile: Profile;
}
interface Profile {
age: number;
city: string;
}What Is the JSON to TypeScript Converter?
The JSON to TypeScript Converter generates ready-to-use TypeScript interfaces from a sample JSON object. Paste a real API response or config object and it infers the type of every field — strings, numbers, booleans, null, nested objects (as their own named interfaces) and arrays (including arrays of objects and mixed-type arrays as unions). You can name the root interface, and it outputs clean, copy-paste-ready definitions. It's a big time-saver when you're typing an API you don't control, converting loosely-typed data to typed code, or scaffolding models from example payloads. Everything runs in your browser — your data never leaves the page.
How It Works
Paste a JSON object, set a name for the root interface, and the TypeScript appears instantly on the right. Copy it into your project. Nested objects become their own interfaces automatically.
When to Use It
Use it when integrating a third-party API, converting untyped JavaScript to TypeScript, generating model types from sample data, or documenting the shape of a JSON payload.
Frequently Asked Questions
- Does it handle nested objects and arrays?
- Yes. Nested objects become separate named interfaces, arrays become typed arrays (e.g. string[]), and arrays with mixed types become unions like (string | number)[].
- Is my JSON sent anywhere?
- No — the conversion runs entirely in your browser. Nothing is uploaded.
- What if a field can be null?
- A null value is typed as null; if you have multiple samples, combine them so optional or nullable fields show up. For full nullability you may want to hand-tweak the output.
Last reviewed: 2026-06-27