JSON to TypeScript Interface Generator
Generate TypeScript interfaces or types from JSON data. Perfect for API responses and data modeling.
JSON Input
TypeScript Output
What is JSON to TypeScript Interface Generator?
This tool automatically generates TypeScript interfaces from JSON data. TypeScript interfaces define the shape of objects, enabling type safety, IDE autocomplete, and compile-time error detection. Instead of manually writing types, paste your JSON and get production-ready interfaces instantly.
How to Use This Tool
- Paste your JSON data (or click Load Example)
- Set the root interface name (e.g., 'User', 'ApiResponse')
- Choose between interface or type syntax
- Click Generate TypeScript and copy the result
Common Use Cases
- Typing API responses in React/Next.js projects
- Creating type definitions for configuration files
- Generating interfaces from database models
- Converting mock data to TypeScript types
Frequently Asked Questions
What's the difference between interface and type?
Interfaces are extendable and better for object shapes. Types are more flexible for unions and intersections. For most API responses, interfaces are preferred. Use types for complex type manipulations.
Should I mark fields as optional?
Use optional fields (?) when properties might be undefined or missing in some responses. This is common for partial updates, optional user fields, or API responses that vary based on query parameters.
How are nested objects handled?
Nested objects are automatically extracted as separate interfaces. For example, a 'profile' object inside 'User' becomes a separate 'Profile' interface, keeping your code organized and reusable.
What about arrays in my JSON?
Arrays are typed based on their first element. An array of objects creates a typed interface (e.g., PostItem[]), while primitive arrays become string[], number[], etc.