What this tool does
It reads your JSON, works out the type of every value, and writes code that describes that shape. Arrays of objects are merged, so a field that appears in only some items is marked optional, and a field that is sometimes a number and sometimes text becomes a union.
Five outputs
TypeScript interfaces for front-end and Node code. Zod schemas that validate data at runtime and give you the type for free. Go structs with json tags, using pointers for optional fields. Python dataclasses with modern type hints. JSON Schema (draft 2020-12) for validators and API docs.
Privacy
API responses often contain real user data. Here it never leaves your browser: the types are generated on this device.
Questions
How are dates handled?
Strings that look like ISO dates become time.Time in Go and get a date check in Zod and JSON Schema. Other languages keep them as strings.
What if my sample is incomplete?
Types can only describe the data they see. Paste a response with as many fields filled in as possible, or several items in an array, for the most accurate result.