JSON to Zod Schema Generator Online
Convert JSON to a Zod schema online. Infers z.string(), z.number(), z.array() and nested z.object() calls with optional keys, ready to paste into TypeScript.
Zod schema will appear here…
To convert JSON to Zod, paste a payload into the left pane. Each value is mapped to its Zod validator — strings to z.string(), numbers to z.number(), nested objects to z.object() — and the right pane returns a schema whose inferred type you can reuse with z.infer.
Zod schemas validate data at runtime and produce a TypeScript type from the same declaration, so the check and the type cannot drift apart. JSON2X maps each value in your payload to its validator — strings to z.string(), numbers to z.number(), nested objects to z.object(), arrays to z.array() — and marks keys missing from some records as .optional().
Why use Zod instead of a TypeScript interface?
Because an interface is a compile-time claim and nothing more. If an API changes a field from a number to a string, your code still compiles and then fails somewhere far from the cause. A Zod schema checks the actual bytes at the boundary and fails immediately with a path to the offending field. Crucially, z.infer derives the static type from the schema, so there is exactly one declaration — you cannot update the validator and forget the type. See the TypeScript generator when you only need the type.
Should I use `parse` or `safeParse`?
parse throws a ZodError on failure, which suits application startup and anywhere a bad value should stop everything — validating environment variables, for instance. safeParse returns a discriminated result ({ success, data | error }) and never throws, which is the better fit for request handlers and fetch wrappers where you want to return a 400 rather than crash. Both give you the same field-level error paths; only the control flow differs.
What should I tighten after generating?
Inference gives you types, not rules. Turn z.string() into z.string().email(), .uuid(), or .datetime() where the field is one of those. Add .min() and .max() to numbers and strings. Replace a plain string with z.enum([...]) where the value set is closed. Add .nullable() where the API can send null — that is distinct from .optional(), which means the key may be absent, and conflating the two is the most common bug in hand-tightened schemas.
How to use the JSON to Zod
Takes under a minute. Nothing is uploaded — every step runs in this browser tab.
- Paste an API payload
Put the object or array into the left-hand input pane. An array of records lets the generator infer which keys are optional.
- Name the schema
Set the exported constant name — the convention is a PascalCase noun such as `UserSchema`.
- Read the generated schema
The right-hand pane shows the Zod schema with nested objects expanded inline and optional keys marked.
- Derive the type
Add `type User = z.infer<typeof UserSchema>` so the static type comes from the validator rather than being written twice.
When to use it
- Validating a third-party API response at the fetch boundary instead of trusting it
- Checking request bodies in a tRPC, Next.js route handler, or Express endpoint
- Parsing and typing environment variables at application startup
- Validating form input with React Hook Form or a similar resolver
- Replacing a hand-written interface with a schema that also checks at runtime
Step-by-step guides for this tool
Task-specific walkthroughs covering the most common ways this tool gets used.
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Frequently Asked Questions
Why use Zod with JSON data?
Zod provides full TypeScript static type inference alongside runtime schema validation, guaranteeing incoming API request payloads adhere strictly to expected shapes.
How do I generate a Zod schema from an API response?
Paste the response and set the root name. Strings become z.string(), numbers z.number(), arrays z.array(...) and nested objects z.object({...}), so the result is a schema you can paste into a route handler and call .parse() on.
Can it export the inferred TypeScript type as well?
Yes. The z.infer toggle appends an exported type derived from the schema, so one paste gives you both the runtime validator and the static type without declaring the shape twice.
What do the strict and nullable options do?
Strict wraps objects with .strict() so unknown keys are rejected instead of stripped. Nullable maps values that were null in your sample to .nullable() rather than guessing a concrete type.
Is this Zod schema generator free, and is my payload uploaded?
It is free with no signup, and nothing is uploaded — generation runs entirely in your browser tab.
Related Developer Tools
- Standards & references:
- Zod
- TypeScript
- JSON
Last reviewed by the JSON2X Engineering Team.