Convert JSON to TypeScript Interfaces Online
You've just opened Postman, hit an API endpoint, and got back a 200-line JSON response. Now you need TypeScript interfaces for your frontend code. You could type them out field by field, checking every type, handling the nested stuff... or you could use our Free JSON to TypeScript Converter to get production-ready interfaces instantly.
How to Use This Tool
Paste Your JSON Payload
Copy your JSON API response or mock data and paste it into the left editor pane.
Instant Type Generation
The engine automatically analyzes the values and generates properly typed TypeScript interfaces on the right.
Copy to Project
Click the copy button and paste the generated interfaces directly into your Next.js, React, or Node.js project.
What is a JSON to TypeScript Converter?
A JSON to TypeScript converter is a utility that parses standard JSON objects and automatically writes the equivalent structural typing definitions required by TypeScript. It drastically reduces boilerplate code. The generated interfaces handle all the fiddly stuff — nested objects get their own interface definitions, arrays infer their element type, union types are created when an array contains mixed types, and optional fields (ones that only appear in some objects) get the ? modifier. It's the same output you'd write by hand, minus the tedium.
🧠 Smart Type Inference
The converter looks at actual values. A "count": 42 becomes count: number. Deeply nested objects are automatically extracted into clean, separate sub-interfaces.
🛡️ 100% Client-Side Privacy
When generating TypeScript interfaces from proprietary APIs, the engine compiles everything locally. Zero data is exposed to remote servers.
When Should You Use This Tool?
- Consuming Third-Party APIs: Quickly generate models for Stripe, Twilio, or GitHub API responses to get intellisense in your IDE.
- Frontend/Backend Contract: When your backend team provides a sample JSON payload instead of a Swagger doc, use this to scaffold your React Query or SWR fetching hooks.
- Migrating JS to TS: When converting a legacy JavaScript codebase to TypeScript, you can run sample data states through this tool to quickly build your store types.
Related JSON Tools
The generated interfaces are a starting point for static typing. For full runtime validation, pair them with our schema generators. You can use our JSON to Zod Converter to generate schemas that automatically infer TypeScript types via z.infer. If you prefer Formik, try the JSON to Yup Converter. For backend Go services consuming the same API, our JSON to Go Structs generator handles json tags automatically. Don't forget to Format your JSON first if you need to debug the raw payload structure!