JSON to TypeScript

JSON to TypeScript is a free browser-based tool that helps you generate typescript interfaces from json. It is part of ToolsMonk's developer tools collection, so you can finish the job without downloading software, creating an account, or jumping between multiple websites.

This tool is especially useful for workflows such as creating typescript types for an api response you have a sample of, bootstrapping interfaces from json config or fixtures, and saving time vs hand-writing types for nested data. Because it runs directly in your browser, you can use it on desktop, tablet, or mobile while keeping the process fast and easy for one-off tasks as well as repeat work.

JSON to TypeScript is designed for people who want a practical, privacy-friendly workflow with instant results inside the larger ToolsMonk library.

JSON to TypeScript generates TypeScript interfaces from a JSON sample, inferring a type for each field from its value — turning the tedious job of hand-writing types for API responses and data into an instant scaffold.

It maps values to types directly (string, number, boolean, nested objects and arrays), which gets the structure right immediately. For real API payloads with deep nesting, that saves significant boilerplate and avoids the transcription errors that creep in when typing interfaces by hand.

The key thing to understand is that inference works from one example, so it can't know which fields are optional or nullable — it only sees what's present in that sample. Treat the output as a strong starting point: review it to mark optional fields (?), add unions or null where your data allows, and name nested interfaces meaningfully. Feeding it a sample that includes the edge cases improves the result.

Generation runs in your browser, so your data — often a real API response — stays private. Pair it with the JSON Formatter, JSON to YAML, and other ToolsMonk developer tools for your full JSON and typing workflow.