JSON to TypeScript Interface Generator
Generate a TypeScript interface from a real JSON sample so you can type an API response without writing every field by hand. This tool parses your JSON, infers the type of each value, and emits named interfaces for nested objects, recursing as deep as your data goes. Arrays are typed by inspecting their items, mixed types become a union, and empty arrays fall back to a safe any array. Nested objects get their own PascalCase interface named after the key, and keys that are not valid identifiers are quoted. Paste a representative JSON object, set the root type name, click generate, and copy the interfaces straight into your project. Everything runs locally in your browser, so the sample data you paste never leaves your machine or gets logged by any service.
How to use JSON to TypeScript
- Paste a representative JSON sample.
- Click convert to generate the interface.
- Copy the TypeScript into your code.
Frequently asked questions
How does it infer types?
It reads a JSON sample and generates a TypeScript interface, inferring field types from the values and creating nested interfaces for nested objects.
How are arrays typed?
Arrays are typed from their elements, so an array of numbers becomes number array and an array of objects gets a matching element interface.
Does it detect optional fields?
It infers optional fields where a sample suggests a value may be missing or null, marking them with a question mark.
What is JSON to TypeScript?
Generate a TypeScript interface from a real JSON sample so you can type an API response without writing every field by hand. This tool parses your JSON, infers the type of each value, and emits named interfaces for nested objects, recursing as deep as your data goes.
Is JSON to TypeScript free to use?
Yes. JSON to TypeScript is completely free, with no sign-up and no usage limits.
Does JSON to TypeScript work in a web browser?
Yes. JSON to TypeScript runs in any modern web browser. There is nothing to download or install.
Is my data private with JSON to TypeScript?
Yes. JSON to TypeScript runs entirely on your device in your browser, so nothing you enter is uploaded to a server.
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