Convert JSON to Zod
schemas online, free & instant
Paste your JSON and generate Zod validation schemas for TypeScript. Runtime type checking, schema inference, and composable validators. Runs entirely in your browser — no upload, no account.
Open JSON to Zod ConverterFrom JSON to type-safe Zod schemas in seconds
No account. No upload. No nonsense.
100% Private
Your JSON never leaves your device. There is no server receiving your data.
Instant Output
Conversion happens as you type. No round-trips to a backend, no latency.
Runtime Safety
Generated Zod schemas enforce types at runtime, not just compile time — real validation for real data.
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Common questions answered
Is the JSON to Zod converter free?
Yes, completely free with no account or signup required. The converter runs entirely in your browser.
What is Zod and why should I use it?
Zod is a TypeScript-first schema validation library that lets you define schemas and validate data at runtime. Unlike TypeScript types which are erased at compile time, Zod schemas enforce types at runtime — catching invalid API responses, form inputs, and config files before they cause bugs.
How does the converter infer Zod types from JSON?
The converter analyzes each JSON value: strings become z.string(), numbers become z.number(), booleans become z.boolean(), arrays become z.array() with inferred element schemas, and nested objects become z.object() with their own field schemas — all composed into a complete validation schema.
Can I use the generated schema with Next.js or tRPC?
Yes. Zod schemas are widely used in the TypeScript ecosystem including Next.js API routes, tRPC procedures, React Hook Form with zodResolver, and environment variable validation with t3-env. The generated schema works with all of these.
Is my data sent to a server during conversion?
No. All conversion runs entirely in your browser using JavaScript. Your JSON is never uploaded or transmitted to any server.
What is Zod schema validation?
Zod is a TypeScript-first schema validation library that validates data at runtime. Unlike TypeScript interfaces (compile-time only), Zod schemas catch invalid API responses, form inputs, and config values that TypeScript alone cannot verify. This tool generates Zod schemas from JSON, giving you both runtime validation and type inference.
The converter maps JSON types to Zod validators: z.string(), z.number(), z.boolean(), z.null(), z.array(), z.object(). Nullable fields use z.nullable() or z.optional(). Output includes z.infer<typeof schema> for automatic TypeScript types — no need to maintain separate interface definitions.
{
"name": "Alice",
"age": 30,
"email": "alice@test.com",
"roles": ["admin"],
"bio": null
}
import { z } from "zod";
const schema = z.object({
name: z.string(),
age: z.number(),
email: z.string().email(),
roles: z.array(z.string()),
bio: z.string().nullable(),
});
type Root = z.infer<
typeof schema>;
Get the most out of this tool
- Use z.infer<typeof schema> to derive TypeScript types from Zod schemas — keeps types and validation in sync.
- Add .min(), .max(), .email(), .url() refinements for more precise validation.
- Zod works with React Hook Form, tRPC, and Remix — use for end-to-end type-safe data validation.
Zod schemas for TypeScript runtime validation
Zod is a TypeScript-first schema declaration and runtime validation library. Unlike TypeScript interfaces (which only provide compile-time type checking), Zod schemas validate data at runtime — checking that an API response or user input actually conforms to the expected shape before your code accesses its fields. A Zod schema is both a runtime validator and a TypeScript type source: z.infer<typeof MySchema> extracts the TypeScript type from the schema, eliminating the need to define types separately.
The converter maps JSON types to Zod validators. JSON strings become z.string(), numbers become z.number(), booleans become z.boolean(), null becomes z.null(), undefined becomes z.undefined(), arrays become z.array(elementSchema), and nested objects become z.object({...fieldSchemas}). Optional fields (fields that might be absent) are wrapped with .optional(), which accepts undefined in addition to the base type. Fields that might be null are wrapped with .nullable().
Zod's parsing approach is important to understand. z.parse() throws a ZodError if validation fails, crashing the current operation. z.safeParse() returns a discriminated union: {success: true, data: T} on success or {success: false, error: ZodError} on failure. For untrusted input (API responses, form submissions, webhook payloads), always use safeParse and handle the error case explicitly. For data you trust (your own code's output), parse is acceptable.
Zod's refinements and transforms add power beyond basic type checking. .refine(fn) adds a custom validation function — for example, checking that a date string is in the past, or that a number is a valid HTTP status code. .transform(fn) converts the validated value — for example, parsing a string date to a Date object, or converting a string enum to a specific union type. Transforms run only after all validations pass, producing the final typed value.
Zod schemas compose naturally. z.union([z.string(), z.number()]) accepts either a string or a number. z.discriminatedUnion('type', [...]) efficiently handles polymorphic data where a "type" field determines the shape of the rest of the object. z.intersection() combines two schemas — both must pass. These combinators let you express complex real-world API response shapes that are impossible to capture with simple TypeScript interfaces.
Zod integration with popular frameworks is excellent. tRPC uses Zod for input and output validation in remote procedure definitions. React Hook Form uses Zod via the @hookform/resolvers/zod adapter for form validation. Next.js API routes use Zod to validate request bodies before processing. Prisma uses Zod for input validation in its generated client. The generated Zod schemas from this tool work with all of these integrations out of the box.
When developers use this tool
Additional frequently asked questions
What is the difference between z.parse() and z.safeParse()?
z.parse() throws a ZodError if validation fails, which crashes the current execution context. z.safeParse() returns a result object — {success: true, data: T} or {success: false, error: ZodError} — without throwing. For untrusted input (API responses, user input), always use safeParse to handle validation failures gracefully. Use parse when you are certain the data is valid and want any failure to be an unhandled exception.
Can I use Zod with Prisma for database input validation?
Yes. Prisma generates Zod schemas for all models via the prisma-zod-generator or zod-prisma packages. Alternatively, manually define Zod schemas matching your Prisma model fields and use them to validate API inputs before passing them to Prisma create/update operations. This prevents invalid data from reaching your database even if Prisma's type system would technically accept it.
How does z.infer work to extract TypeScript types?
z.infer<typeof MySchema> is a TypeScript utility type that extracts the output type of a Zod schema. If MySchema is z.object({name: z.string(), age: z.number()}), then z.infer<typeof MySchema> equals {name: string, age: number}. This lets you define your type once (in the Zod schema) and derive the TypeScript type from it, rather than defining them separately and risking them diverging.
Is Zod better than io-ts or Yup for runtime validation?
Zod is the most popular choice for TypeScript projects today due to its excellent TypeScript inference, clean API, and active development. io-ts is more powerful but has a steeper learning curve based on functional programming concepts. Yup is simpler and more focused on form validation (widely used with Formik). For general-purpose runtime type validation in TypeScript, Zod is the current recommended choice.