JSON to Zod Schema

TypeScript Types Are Compile-Time. Zod Validates at Runtime.

Your TypeScript interfaces tell the compiler what shape your data should be. But at runtime? TypeScript’s gone. If your API returns a malformed response, your interface won’t catch it — you’ll get a silent undefined or a crash three function calls later.

Zod bridges that gap. It defines schemas that validate data at runtime and infer TypeScript types at compile time. You get type safety AND runtime protection. But writing Zod schemas by hand from a complex JSON structure is tedious — especially for nested objects with arrays of objects containing more arrays.

Paste your JSON here and get complete Zod schemas with z.object(), z.string(), z.number(), z.boolean(), z.array(), nested schema definitions, type exports, and the import statement. Ready to paste into your project.

The Output

{"name": "John", "age": 30, "active": true} becomes:

import { z } from "zod";

const RootSchema = z.object({
  name: z.string(),
  age: z.number(),
  active: z.boolean(),
});

type Root = z.infer<typeof RootSchema>;

Import statement included. Type export included. Copy and paste.

Where Zod Schemas Earn Their Keep

API response validation. Your frontend calls /api/users and expects a specific shape. Wrap the fetch response in RootSchema.parse() and malformed data throws immediately instead of causing subtle bugs downstream.

React Hook Form. Zod integrates directly with React Hook Form via @hookform/resolvers/zod. Generate the schema from sample form data, add .email(), .min(), and .max() refinements, and your form has type-safe validation with good error messages.

tRPC. tRPC uses Zod schemas for input validation on your API routes. Generate the base schema from sample input, refine it, and your API is type-safe from client to server.

Environment variables. Parse process.env through a Zod schema at startup. Missing or invalid env vars fail fast with clear error messages instead of causing cryptic runtime errors.

Refining After Generation

The generated schema is a starting point. Add refinements like:

• z.string().email() for email fields
• z.string().url() for URLs
• z.number().min(0).max(100) for bounded numbers
• z.string().nullable() instead of z.null() when a field can be either a string or null
• .optional() for fields that might be missing entirely

For arrays with mixed types, the tool infers from the first element. Adjust to z.union() if needed.

The JSON to TypeScript converter produces compile-time interfaces without runtime validation. Use both: Zod for runtime boundaries (API responses, form input), interfaces for internal types.

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