JSON to TypeScript converter tool icon
Data & JSON tools

JSON to TypeScript converter

Infer TypeScript types from sample JSON and generate interface/type declarations. Handles nested objects, arrays and union types for quick API modeling and autocomplete.

JSON input
TypeScript output
Tip: this tool infers types from sample JSON; mixed arrays or dynamic keys may become union types or unknown. Everything runs locally in your browser.

Usage & Instructions

1. Paste your JSON data into the input box on the left. 2. Set the root type name in the toolbar above (default is Root). 3. Choose the output mode (Interface or Type Alias). 4. Optional settings: Quote keys, Semicolons. 5. The tool automatically parses and generates TypeScript definitions. 6. Click "Copy result" to copy the generated code to your clipboard.

Tips

**Local Processing** All conversions happen entirely within your browser via JavaScript. No data is sent to any server, ensuring your privacy.

**Smart Type Inference** Automatically identifies strings, numbers, booleans, arrays, and nested objects. For mixed-type arrays, it attempts to generate Union Types.

**Interface vs Type** Choose between `interface` and `type`. Interfaces are better for object structures and inheritance, while Type Aliases are more flexible for union types or primitive aliases.

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