How It Works
This tool parses your JSON input and recursively walks through every key and value to build a matching Zod schema. Nested objects become nested z.object() calls, arrays are analyzed to determine the element type, and null values are converted to .nullable() modifiers.
The conversion runs entirely in your browser. No data is sent to any server, making it safe for proprietary API responses and sensitive payloads.
Why Use Zod for Validation?
Zod is the most popular runtime validation library in the TypeScript ecosystem. Unlike plain TypeScript interfaces that vanish at runtime, Zod schemas give you:
- Runtime safety — validate API responses, form data, and environment variables before they reach your business logic.
- TypeScript inference — extract static types from your schemas with
z.infer<typeof schema>, so you never write a type definition twice. - Composability — merge, extend, pick, and omit schemas just like you would with types.
- Descriptive errors — Zod returns structured error objects that tell you exactly which field failed and why.
- Framework support — first-class integrations with React Hook Form, tRPC, Next.js server actions, and more.
Supported Features
| Feature | Example Input | Generated Output |
|---|---|---|
| Strings | "name": "Alice" | name: z.string() |
| Numbers | "age": 30 | age: z.number() |
| Booleans | "active": true | active: z.boolean() |
| Null values | "bio": null | bio: z.unknown().nullable() |
| Nested objects | "address": { "city": "NY" } | address: z.object({ city: z.string() }) |
| String arrays | "tags": ["a", "b"] | tags: z.array(z.string()) |
| Object arrays | "users": [{ "id": 1 }] | users: z.array(z.object({ id: z.number() })) |
| Mixed arrays | "data": [1, "two", true] | data: z.array(z.union([z.number(), z.string(), z.boolean()])) |
| Empty arrays | "items": [] | items: z.array(z.unknown()) |
FAQ
Is my data safe?
Yes. The entire conversion happens client-side in your browser using JavaScript. Your JSON is never transmitted to a server. You can verify this by opening your browser's Network tab — no requests are made when you paste or convert.
Can I use the output directly in my project?
Yes. Click the Copy button and paste the schema into your .ts file. The generated code requires zod as a dependency (npm install zod). The import statement is included in the output.
What about optional fields?
Fields with a null value are generated with the .nullable() modifier. When processing arrays of objects, if a field appears as null in some items but has a value in others, it is correctly marked as nullable. For truly optional fields (that may be absent entirely), you can add .optional() manually after generating the base schema.
Zod vs Yup vs Joi — which should I use?
Zod is the best choice for TypeScript projects because it was built from the ground up for TypeScript. Unlike Yup and Joi, Zod gives you automatic type inference with z.infer, requires no separate type definitions, and has zero dependencies. Yup and Joi are still valid options for JavaScript-only projects or legacy codebases.
Does this handle deeply nested JSON?
Yes. The tool recursively traverses your JSON structure to any depth. Each nested object generates a nested z.object() call, keeping the schema self-contained and easy to read.
Need TypeScript interfaces instead? Try our JSON to TypeScript converter.