JSON API to TypeScript — Interfaces from Responses

Generate TypeScript Interfaces from API JSON

Generate TypeScript interfaces from REST API JSON responses. Paste any payload and get strongly-typed interfaces and type aliases instantly. Free.

Paste any REST API response JSON and instantly generate TypeScript interfaces and type aliases. No more hand-writing types from API documentation — get accurate, strongly-typed interfaces in seconds.

TypeScript Interfaces from Real API Responses

Hand-writing TypeScript interfaces from API documentation is slow and error-prone. Paste the actual JSON response and our inference engine generates accurate types that match the real data — not just the docs.

Type Inference Logic

JSON string → string
JSON number → number
JSON boolean → boolean
JSON null → null (or optional ?)
JSON array of objects → ChildType[] with separate interface
Mixed arrays → union type (string | number)[]

Combining with Zod for Runtime Validation

Generate matching Zod schemas alongside TypeScript interfaces using our JSON to Zod tool for full compile-time and runtime type safety.

Who this guide is for

Generate TypeScript interfaces for fetch() and axios API responses
Create types for React component props from API data shapes
Type tRPC and React Query responses without manual interface writing
Generate interfaces for third-party API SDKs (GitHub, Stripe, OpenAI)

Frequently Asked Questions

How accurate are the generated TypeScript interfaces?

The interfaces match the actual JSON sample exactly. If the API can return additional fields or nullable variants not in the sample, you may need to add | null or optional markers manually.

Can I generate types for paginated API responses?

Yes. Paste the full paginated response JSON (including the wrapper object with meta, data array, etc.) and all levels will be typed.

How do I use these TypeScript interfaces in a React project?

Copy the generated interfaces and paste into your .ts or .d.ts file. Then use them as useState<ApiResponse>() or as function return types.