JSON to Zod

Turn a JSON sample into a TypeScript Zod Schema. Generated locally so frontend validation and Structured Output can share one rule set.

If the frontend already validates forms or APIs with Zod, you don't have to write z.object again. Paste a sample and get common z.string / z.number / z.array structure.

Output usually includes z.infer so you can use the type directly. If the project is moving between Zod 3 and 4, tweak the generate to match the repo.

Conversion stays in the browser. You don't have to upload a response sample to an online codegen site.

How this differs from a handwritten interface

An interface is types only — bad data still gets through at runtime. Zod can parse, and on failure it tells you which field is wrong.

Common edits after generate

Make optional fields .optional(), nullable fields .nullable(), enums z.enum, and date strings a refine. Don't leave every key required.

How to use it

Paste a JSON sample — a real API response is best.
Click Generate Zod and copy the TypeScript on the right.
Change some fields to optional / nullable / enum for the business.
Use z.infer as the type, or export it to compare with Structured Output.
After the frontend is wired, safeParse a second response.

When to use it

Add runtime checks for API responses in a Next.js / React project.
Share one field list with Structured Output so you don't keep two rule sets.
Generate Zod from a sample, then hand-write superRefine for cross-field rules.
Treat Zod as docs: a new teammate can read the schema and see the object.

Keep in mind

Inference is optimistic. Keys that appeared in the sample often become required.
Unions, recursive structures, and branded types need a hand write.
It does not replace server validation. It only thickens the frontend guardrail.

FAQ

Is the output Zod 3 syntax?

You get common z.object / z.array / z.string structure. Tweak it for your project's Zod version.

Does it generate TypeScript types?

It includes z.infer, so you can use the type directly and skip a handwritten interface.

Are nested objects supported?

Common nesting and arrays are supported. Very deep or recursive types should be split by hand.

Is the JSON uploaded?

No. Conversion stays in the browser.

Can it generate validation error copy?

No business messages by default. Add .min / .email message yourself for localized errors.

How is this different from To code?

To code emits interface / struct. This page emits an executable Zod schema.

How do I tell optional from nullable?

Use optional when the key may be missing; nullable when the key is present and the value is null. The sample cannot decide that for you.

Can I use it on the server?

The same schema can run in Node. Still validate again at the gateway or backend.