JSON to TypeScript

This free JSON to TypeScript converter turns a JSON sample into clean TypeScript definitions, inferring types for strings, numbers, booleans, arrays and nested objects. Unlike a naive converter, it merges the shapes of every object in an array into one interface, marking fields that are missing from some elements as optional, and itreuses identical interfaces instead of emitting duplicates. Paste a real API response and get typed models in seconds.

Tune the output to match your codebase: choose between interfaceand type, add export declarations, prefix names (e.g. I for IUser), pick your indent, mark every field optional, prefer | null over the optional ?, or emit readonly properties. Turn on ISO date detection to type timestamp strings as Date, andstring-enum inference to collapse a small, repeating set of string values (like a status field) into a literal union such as "active" | "archived".

Both panes are syntax-highlighted as you type, invalid JSON is flagged inline with the parser's own message, and you can open or drag in a.json file, then copy or download the generated.ts definitions.