JSON→TypeScript変換

This is a JSON to TypeScript generator that infers a set of interfaces from an example JSON object or array, so you can paste an API response and get ready-to-use types instead of writing them by hand.

It is a big time-saver when you are consuming an API or a config file: paste a response, optionally name the root interface, and copy clean TypeScript straight into your code.

Generation runs entirely in your browser, so your data never leaves your device, which matters when the sample contains real values.

It handles real-world shapes: nested objects become their own named interfaces referenced from the parent, arrays of objects are merged into one interface, and union types are produced where values vary.

When the objects in an array do not all have the same keys, the keys missing from some elements are marked optional with a question mark, which matches how the data actually behaves and keeps the types honest.

One important point: it infers a shape from the single sample you give it, rather than enforcing a schema. If a field is sometimes null or absent in real data but not in your sample, the generated type will not know that, so use a representative example.