JSON to Zod Schema Generator

TypeScript checks your code, not your data. An interface for an API response is a promise the compiler can't verify, because the response only exists at runtime. Zod closes that gap: you describe the shape once, Zod validates real data against it, and z.infer derives the static type, so the type and the check can never drift apart.

import { z } from "zod";

// Zod 4. In Zod 3: z.number().int(), z.string().email(), z.string().datetime()
const UserSchema = z.object({
  id: z.int(),
  email: z.email(),
  createdAt: z.iso.datetime(),
});
type User = z.infer<typeof UserSchema>;

const user = UserSchema.parse(await res.json()); // typed and checked

Use it wherever untrusted data enters your program: fetch responses, form input, webhooks, message queues, environment variables and localStorage.

Schemas are written in dependency order, so each one is declared before another schema uses it, and every schema gets a matching export type. When a date-time in your sample carries a UTC offset such as +05:30, the generator adds { offset: true }, because by default Zod only accepts the Z suffix.

Choose these deliberately. An API that sends "middleName": null and one that leaves middleName out are different contracts, and Zod rejects the one you didn't declare. That is exactly what you want from a validator: a clear error at the boundary instead of an undefined deep inside your app.

Zod 4, released in 2025, keeps the familiar API but moves string formats to the top level and tightens a few defaults. The generator writes this style by default:

• z.email(), z.url(), z.uuid() and z.iso.datetime() replace z.string().email() and friends, which still work but are deprecated.
• z.int() only accepts safe integers, so an ID above 2^53 fails validation. The generator falls back to z.number() for such fields, in both versions.
• z.strictObject() and z.looseObject() replace the .strict() and .passthrough() methods.

Choose Zod 3 for a project still on Zod 3, or for shared code that must run on both: the Zod 3 syntax this generator writes runs on both major versions. Either way, z.object() strips unknown keys from the parsed result by default; turn on Strict objects to reject them instead.

parse() throws a ZodError, while safeParse() returns a result you branch on, which keeps control flow explicit:

const result = UserSchema.safeParse(data);
if (!result.success) {
  console.error(result.error.issues); // each issue has a path and a message
  return;
}
const user = result.data; // fully typed

Each issue carries a path to the failing field, which maps straight onto form fields and log messages. Form libraries such as React Hook Form (through @hookform/resolvers) and API frameworks such as tRPC accept Zod schemas directly. Need plain types without runtime checks? The JSON to TypeScript generator writes interfaces from the same sample.