The JSON to TypeScript Converter transforms JSON data into strongly-typed TypeScript interfaces and type aliases in seconds. Whether you're integrating with a REST API or structuring complex data models, this tool generates clean, ready-to-use TypeScript definitions. All conversion happens locally in your browser — your data never leaves your machine.
Detailed Functionality
The converter analyses the structure of any JSON object or array and produces idiomatic TypeScript definitions. Nested objects are automatically extracted into separate named interfaces, keeping your code organised and reusable.
Key options:
- Root name — customise the name of the top-level interface (default: `Root`).
- export keyword — adds `export` before every generated interface or type alias, making it ready for module imports.
- Optional fields (?) — marks properties whose value is `null` or `undefined` as optional.
- Use type alias — generates `type Foo = { … }` instead of `interface Foo { … }`.
The tool handles all JSON primitives (`string`, `number`, `boolean`, `null`), nested objects, and arrays — including arrays of objects, mixed-type arrays, and empty arrays.
Practical Examples
Example 1: API response → TypeScript
Paste a REST API response into the input, set the root name to `ApiResponse`, enable `export`, and click Convert. You get a full set of interfaces ready to paste into your TypeScript project.
Example 2: Deeply nested config file
JSON configuration files with multiple nesting levels are handled automatically. Each nested object becomes its own named interface, so the output stays clean and reusable.
Example 3: Array of objects
If the root JSON value is an array, the tool generates a type alias for the array and an interface for the element type, e.g. `export type Users = UserItem[];`