๐โ๐ JSON to TS
Generate TypeScript interfaces from JSON automatically. Free, instant, handles nested objects and arrays. No upload needed.
๐โ๐ JSON to TS
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About the JSON to TS Tool
Writing TypeScript interfaces by hand for an API response is tedious and prone to drift. A payload with thirty fields and three levels of nesting takes real time to type out, and one typo produces a type error that has nothing to do with your actual code.
This generator infers types directly from a sample JSON response and produces ready-to-use interface declarations, including nested interfaces for sub-objects and array element types. It is the fastest way to add type safety to code consuming an untyped API. Generation runs in your browser, so response samples containing real data stay private.
How to Use JSON to TS
- Paste a representative JSON response into the input area.
- Set a name for the root interface.
- Press Convert to generate the TypeScript declarations.
- Copy the interfaces into your types file.
When to Use This Tool
- Typing an API response in a TypeScript frontend
- Generating types from a third-party service with no published definitions
- Creating interfaces for configuration objects
- Bootstrapping types during a JavaScript to TypeScript migration
- Producing type definitions for JSON test fixtures
Things Worth Knowing
- Types are inferred from the sample provided. Optional fields absent from your sample will not be marked optional.
- Null values produce a null type โ you will usually want to widen these to a union manually.
- Empty arrays cannot be typed, since there is no element to inspect.
Quick Facts
| Tool name | JSON to TS |
| Category | Developer Tools |
| Price | Free โ no account, no trial, no watermark |
| Where it runs | Entirely in your browser (client-side) |
| Files uploaded | None โ your data never leaves your device |
| File size limit | None imposed; limited only by device memory |
| Works offline | Yes, once the page has loaded |
| Platforms | Windows, macOS, Linux, Android, iOS |
Frequently Asked Questions
How does it know which fields are optional?
It cannot, from a single sample. Every field present is typed as required. Review the output and add ? to fields your API may omit.
What happens with an empty array?
It produces any[] or unknown[], because there is no element from which to infer a type. Supply a sample containing at least one element for accurate results.
Does it handle deeply nested objects?
Yes. Nested objects generate their own named interfaces, which are referenced from the parent rather than inlined, keeping the output readable.
Should I use interface or type?
Interfaces are conventional for object shapes and support declaration merging. Type aliases are more flexible for unions and mapped types. For API response shapes, interfaces are the usual choice.