Automatically convert JSON data to TypeScript interface/type definitions, supporting nested objects and arrays
Zero Dependencies Β· Works Offlineπ₯ JSON Input
π TypeScript Interface
What Can the JSON to TypeScript Interface Tool Do?
The JSON to TypeScript Interface tool is a free online developer tool that automatically converts JSON data into TypeScript interface or type definitions. It supports nested objects, arrays, and basic type inference, automatically generating multiple interface definitions. Options like export and readonly can be configured. Suitable for API response type definitions, data model generation, and TypeScript project initialization. All computation happens on your device β JSON to TypeScript Interface, other values and other inputs stay in your browser.
Core Features
- Auto Type Inference: string/number/boolean/null automatically identified
- Nested Objects: Automatically split into separate interface definitions
- Array Types: Infer element types, support union type arrays
- Configurable: export/readonly/root interface name adjustable
- Complete Code: Generate ready-to-use TypeScript code
How to Use
1. Paste JSON data in the input box.
2. Adjust options (interface name, export, readonly).
3. Click "Generate Interface" to see TypeScript code.
4. Click "Copy Code" or "Download TS" to get the result.
Use Cases
Case 1: API Type Definitions
Automatically convert API response JSON to TypeScript interfaces for quick type safety.
Case 2: Data Models
Generate TypeScript type definitions from JSON configuration or data samples.
Case 3: Project Migration
Convert JavaScript project JSON data to TypeScript interfaces, accelerating typed migration.
Technical Background
TypeScript interfaces define the shape of objects, providing compile-time type checking. When inferring types from JSON, null values generate union types (e.g., string | null), arrays are inferred based on elements (e.g., number[]), and nested objects are automatically split into separate interfaces. The difference between type and interface: interfaces support declaration merging, while types support union/intersection types. In real projects, consider combining with JSDoc for property documentation, and using tools like json-schema-to-typescript for more complex scenarios.
β FAQ
What JSON structures are supported?
Supports objects, arrays, nested objects, and basic types. Types are automatically inferred.
Can the generated interfaces be used directly?
Yes. The code follows TypeScript standard syntax. Paste directly into a .ts file.
How are null values handled?
Null values are marked as union types like string | null.
Does it support array type inference?
Yes. Arrays are inferred as Type[] based on elements. Mixed types become union type arrays.
Is my data uploaded to a server?
No. All type inference and code generation is done locally in your browser.
What is the difference between interface and type?
Interfaces support declaration merging, types support union/intersection types. This tool generates interfaces by default.