JSON to Zod / Yup Schema Generator
Convert any JSON object or array into a Zod or Yup validation schema instantly. Handles nested objects, arrays, null values, and union types — all in your browser, no sign-up needed.
JSON → Zod / Yup Schema Generator
What does this tool do?
This tool reads a JSON object or array and generates a matching runtime validation schema for either Zod or Yup. It handles all primitive types (string, number, boolean, null), nested objects, arrays of any type, and null-union fields — saving you the tedium of hand-writing schemas for API responses or form payloads.
Zod vs Yup
Zod is a TypeScript-first schema library that infers static types from your schema, making it ideal for full-stack TypeScript projects. Yup is the classic choice for React form validation (especially with Formik), offering a fluent chainable API. Both produce equivalent runtime validation logic — choose whichever your project already uses.
Handling null values
When a JSON field is null, the tool cannot determine the true runtime type. In Zod, null fields are generated as z.union([z.TYPENAME(), z.null()]) or z.null() when no other type hint is available. In Yup, null fields become yup.mixed().nullable(). Enable 'Required fields' for Yup to append .required() to every field.
How to use
- Paste a JSON object or array into the input area.
- Choose Zod or Yup output using the toggle.
- Optionally set the variable name and enable strict mode (Zod) or required fields (Yup).
- Click Generate Schema to produce the schema code.
- Click Copy to copy the result to your clipboard.
Your JSON stays in your browser — no data is sent to any server.
Frequently Asked Questions
- Does it handle nested objects?
- Yes. Nested objects are converted to nested z.object({...}) or yup.object({...}) schemas inline — no separate type declarations needed.
- What happens to null values?
- Null values are represented as z.null() in Zod, or yup.mixed().nullable() in Yup, since the true underlying type cannot be inferred from the JSON sample alone.
- What is Zod strict mode?
- Calling .strict() on a Zod object schema makes it throw a validation error if the input contains keys not present in the schema. It is useful for APIs where unexpected extra fields should be rejected.
- Does it support arrays of objects?
- Yes. Arrays of objects generate z.array(z.object({...})) for Zod or yup.array().of(yup.object({...})) for Yup, with the nested schema inferred from the first item.
- Is this tool free?
- Yes — completely free, no sign-up required. All schema generation happens locally in your browser.