Type helper

JSON to TypeScript types

Paste any JSON and instantly generate a TypeScript type definition.
Objects and arrays are inspected to infer field names and nested shapes,
so you can drop the output straight into your codebase.

Nothing is sent to a server—parsing and type generation run entirely in your browser.

Enter JSON

Generated TypeScript

Guide

How to use & features

Paste JSON into the input and click “Convert to TypeScript.”
Objects are formatted into a structured block with typed properties.
Arrays are analyzed to determine element types; mixed content becomes a union.
Use the copy or clear buttons to reuse the output or start over.

Samples

Sample input & output

Generate TypeScript types

Input

{"title":"Draft","tags":["dev","web"],"stats":{"views":1200}}

Output

type Root = {
    title: string;
    tags: string[];
    stats: {
        views: number;
    };
};

FAQ

Frequently asked questions

Do you output interfaces or type aliases?

The tool outputs TypeScript interfaces by default, deriving property names and types from the JSON structure.

Are arrays and nested objects supported?

Yes. Array element types are inferred, and nested objects are composed recursively into the generated types.

How are optional properties decided?

If a field is missing in parts of the sample, it is treated as optional. You can fine-tune the output afterwards as needed.

Use cases

Common use cases

Bootstrapping type definitions
Generate TypeScript interfaces from sample backend responses to kick off a type-safe implementation quickly.
Aligning contracts
Turn shared JSON into types to clarify expectations about field names, optional flags, and shapes.
Lightweight review snippets
Produce minimal interfaces you can paste into PR comments to focus discussion on structure over typos.

Notes

Notes & limitations

Work stays in your browser
Inputs and outputs remain local. Closing the tab or clearing cache will remove any temporary state.
Validate critical data
Results are helper outputs—double-check them before sending to production systems or sharing externally.
Large payloads depend on your device
Very large text or files can feel slow in some browsers. Use a desktop environment for heavy workloads.