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JSON to TypeScript Interface Converter

Generate TypeScript types from JSON

JSON to TypeScript Converter

Generate TypeScript interfaces and type definitions from JSON data automatically. Converting API responses to TypeScript types enables compile-time type checking, IDE autocomplete, and better code documentation. This tool analyzes JSON structure and produces accurate TypeScript definitions instantly.

Why Convert JSON to TypeScript

TypeScript's type system catches errors at compile time rather than runtime. When working with external APIs, manually creating type definitions is tedious and error-prone. Automated conversion ensures your types accurately match the actual data structure, reducing bugs and improving developer experience.

Benefits of proper typing:

  • Compile-time error detection - Catch typos and wrong assumptions early
  • IDE autocomplete - Code faster with intelligent suggestions
  • Self-documenting code - Types describe data shape
  • Refactoring confidence - TypeScript catches breaking changes

Conversion Example

Input JSON: ``json { "id": 123, "name": "John Doe", "email": "john@example.com", "roles": ["admin", "user"], "settings": { "theme": "dark", "notifications": true } } `

Output TypeScript: `typescript interface User { id: number; name: string; email: string; roles: string[]; settings: Settings; }

interface Settings { theme: string; notifications: boolean; } ``

Type Inference Rules

| JSON Value | TypeScript Type | Notes | "string"stringAll text values 123numberIntegers and floats true / falsebooleanBoolean literals nullnullExplicit null [...]Type[]Array of inferred type {}InterfaceNested object type

Interface vs Type Alias

FeatureInterfaceType Object shapesPreferredSupported Extensionextends& intersection Declaration mergingYesNo | Union types | No | Yes |

For JSON conversion, interfaces are generally preferred because they can be extended and merged.

Use this converter to quickly generate TypeScript types from your API responses and maintain type safety throughout your application.

Frequently Asked Questions

Why convert JSON to TypeScript?

TypeScript interfaces provide compile-time type checking, IDE autocomplete, and better code documentation. Converting API response JSON to interfaces catches type mismatches early and improves code quality.

Interface vs Type in TypeScript?

Interfaces are better for object shapes (like API responses) because they can be extended and merged. Types are better for unions, primitives, and computed types. For JSON conversion, interfaces are typically preferred.

How should I handle optional fields?

Fields that may be null or missing should use optional syntax (field?: type) or union with null (field: type | null). Check your API documentation to determine which fields are guaranteed vs optional.

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