JSON to TypeScript Interface Generator

What is JSON to TypeScript conversion?

JSON describes data; TypeScript types describe the shape of that data so your editor and compiler can catch mistakes before your code runs. This tool reads a JSON sample and infers matching TypeScript types automatically — including nested objects, array item types, and fields that don't appear in every record.

Interface, type, or Zod schema — which one do I need?

Interface and type are both compile-time-only TypeScript constructs — they disappear when your code is built and don't check anything at runtime. Use interface if you're describing an object shape you might extend later; use type if you need unions, tuples, or you just prefer type aliases. Zod generates an actual JavaScript object that validates data while your app is running — useful when the JSON comes from an API you don't fully control, since it can catch unexpected data at the boundary instead of failing silently deeper in your code.

How the inference works

For arrays of objects, the tool looks at every item: a field becomes optional if it's missing from at least one item, and becomes a union (like string | number) if items disagree on its type. Nested objects get their own named interface, generated from the key or singularized array name (so a users array produces a User interface).

Frequently asked questions

Does this upload my JSON anywhere?
No. Parsing and type generation happen entirely in your browser; nothing is sent anywhere.

What if my array items have different fields?
The tool merges every item in the array, marking fields that aren't present everywhere as optional, and unioning fields whose type differs between items.

Can I use the Zod output for form or API validation?
Yes — Zod schemas are commonly used to validate API responses, form submissions, or environment variables. Install zod in your project and import the generated schema.