JSON to TypeScript Types
Generate TypeScript type definitions from a JSON sample, with nested types handled.
Types that match your data
Hand-writing TypeScript types to match a JSON structure is tedious and easy to get subtly wrong, particularly with nesting. This infers TypeScript types from a JSON sample — generating the interfaces or type aliases, naming the nested shapes, and typing each field — so you get a solid, correctly-structured starting point in seconds.
Paste a representative JSON sample and the TypeScript types are generated.
Inference has blind spots to fill
Because the types come from a single sample, they are a draft to refine rather than a finished contract. Inference cannot know a field is optional if your sample always includes it, that a string is really a union of specific literals, that a number might sometimes be null, or what type an empty array should hold. Generate the types, then apply that domain knowledge: mark optional fields, narrow loose types, and handle nullability. That combination gives you accurate types far faster than writing them by hand, without inheriting the blind spots of pure inference.
Questions & answers
How reliable are the generated types?
They are an accurate starting point from your sample, but refine them — inference cannot know which fields are optional, nullable, or fixed unions.
Does it handle nested objects?
Yes — nested shapes are given their own types and the structure is reflected in the output.
Is my JSON uploaded?
No. The types are generated in your browser.