JSON to TypeScript
Instantly convert JSON to TypeScript interfaces and type definitions. Supports nested objects, arrays, and union types.
What does JSON to TypeScript conversion do?
It analyzes your JSON data structure and generates corresponding TypeScript type definitions, including interfaces and type aliases with proper typing for all nested structures.
What is the difference between interface and type alias?
Interfaces are extendable and better for defining object shapes. Type aliases can represent unions, intersections, tuples, and primitive types. Both work similarly for simple objects.
Does it handle nested JSON objects?
Yes, the converter recursively processes nested objects and generates separate named interfaces for each nested structure, named after their parent key.
How are arrays with mixed types handled?
Mixed-type arrays generate union types (e.g., string | number). Arrays of objects with a common schema generate a single interface for the element type.
Can I use the generated types in my project?
Yes, the generated TypeScript code is clean, production-ready, and can be directly copied into your project files.
Does it work with large JSON files?
Yes, the converter handles large JSON payloads efficiently with instant processing in your browser.
Is the JSON data sent to a server?
No, all conversion happens entirely in your browser. Your JSON data never leaves your device.
How are null values handled?
Null values are typed as the union of the expected type and null (e.g., string | null), ensuring type safety.
Can I generate types from API responses?
Yes, simply paste the JSON response from any API and the tool will generate matching TypeScript definitions.
Does it support JSON arrays at the root level?
Yes, if the root of your JSON is an array, the tool generates a type alias for the array element type.
Why use TypeScript types instead of plain JavaScript?
TypeScript adds static type checking that catches errors at compile time, provides better IDE autocomplete, and serves as living documentation for your data structures.
How to Use JSON to TypeScript
Generate TypeScript interfaces or type aliases from JSON without leaving your browser. Conversion is fully local — your sample payloads are never uploaded.
- Paste a JSON sample into the input editor; matching TypeScript definitions appear in the output panel.
- Enter the top-level type name in "Root Name:", for example ApiResponse or UserProfile.
- In "Style:" choose interface for classic object types or type for union-friendly aliases.
- Toggle "Optional fields" to mark missing keys with ?, "Export keyword" to prefix export, and "Readonly fields" for immutability.
Arrays with mixed element types merge into one union — enable "Optional fields" afterwards to hand-tune properties that appear in only some objects.
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