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JSON to TypeScript

Generate TypeScript interfaces and types from JSON data automatically

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About This Tool

The JSON to TypeScript converter generates clean TypeScript interfaces and type definitions from your JSON data. It intelligently infers types, handles nested objects and arrays, and produces idiomatic TypeScript code. Perfect for front-end developers who need to type API responses or configuration objects without manually writing interfaces.

Key Features

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Use Cases

json typescript interface types code-generation

Frequently Asked Questions

How are JSON types mapped to TypeScript types?

Strings map to string, integers and floats map to number, booleans map to boolean, null maps to null, arrays map to Array<T>, and objects map to nested interfaces. Fields with null values generate union types (e.g., string | null).

What is the difference between interface and type alias?

Interfaces can be extended and merged, making them ideal for defining object shapes. Type aliases are more flexible, supporting union types, intersection types, and tuples. For simple object structures, they are functionally equivalent — choose based on your project conventions.

How are optional properties handled?

Fields with null values are marked as optional properties using the ? modifier, indicating the field may be absent. You can also choose to generate union types (e.g., string | null) to explicitly indicate the field may be null.

Can I customize the interface name?

Yes. You can set a custom root interface name in the options. Nested interface names are derived from JSON key names in PascalCase.

Is my data safe when using this tool?

Absolutely. All conversion happens locally in your browser. No JSON data is uploaded to any server, ensuring your information remains completely private and secure.