JSON to TypeScript Converter — free browser tool for developers

JSON to TypeScript Converter – Paste JSON, Get Interfaces

If you work with APIs or config files, you’ve probably found yourself writing TypeScript interfaces by hand to match JSON structures. It’s repetitive, error-prone, and honestly, kind of boring.

I built JSON to TypeScript Converter to cut that noise. Paste in some JSON, and it gives you clean, properly typed interfaces—right in the browser, no setup needed.

It handles nested objects, arrays, optional fields (based on null values), and even generates readable names for nested types. You can tweak settings like interface naming, nullability, and export options. There’s also syntax highlighting and basic validation so you’re not pasting malformed JSON by accident.

The tool is free to use. No sign-up, no tracking, no limits on conversions. Just open, paste, copy.

There’s also a Pro tier ($9/month) that adds a few quality-of-life features:

• Custom type mapping – replace inferred types (e.g., map "id": "abc" to string or ID)
• Export as multiple files – useful for larger schemas
• Save and load JSON samples – handy for reusing API responses
• Dark mode – because not everyone codes in daylight

I use this daily when integrating third-party APIs or prototyping new features. It doesn’t replace proper schema validation or codegen pipelines, but it speeds up the early stages—especially when you just need something working fast.

It’s built with Preact and Monaco Editor, runs entirely in-browser (your data stays local), and is hosted on Vercel.

Try it: https://tool-json-to-typescript-converter.vercel.app

Feedback? Issues? GitHub repo is public — feel free to open an issue or drop a comment here. I’m planning to add support for enums and union types detection based on common patterns, but happy to hear what else would make this more useful.