JSON to TypeScript Interface Online

When consuming a new REST API in a modern React or Next.js application, manually writing TypeScript interfaces for massive nested JSON responses is incredibly tedious and prone to typos. This tool is built to let you paste a raw JSON payload and instantly generate perfectly structured, deeply nested TypeScript interfaces.

Static Type Inference

TypeScript relies on static typing to provide IDE autocomplete and catch bugs at compile-time. This tool doesn't just do a simple string replace; it acts as a primitive type-inference engine. It recursively crawls through your JSON object, identifying if a value is a string, number, boolean, or a nested Array. It then constructs the corresponding interface, extracting nested objects into their own named interfaces (like export interface UserAddress { ... }).

Handling Arrays and Unions

APIs often return arrays. If the tool detects an array of strings (["admin", "user"]), it automatically types it as string[]. If it detects an array of complex objects, it will create a new interface for that object and type the array accordingly (e.g., items: CartItem[]). It saves hours of manual structural mapping.

Avoiding Data Leaks

Pasting proprietary backend API structures into a random online tool can expose your company's internal data models. This tool runs the AST generation and type-inference algorithms entirely within your local browser's memory, ensuring your schema never touches an external server.