Which Zod version does this target?

The output uses z.object, z.array, z.union, .optional(), .nullable(), and z.infer, which work the same in Zod 3 and Zod 4.

Why is each schema followed by a type?

z.infer gives you the TypeScript type from the schema, so the validator and the type cannot drift apart.

No. The schema is generated in your browser.

Paste a JSON sample. A Zod schema and its type are written beside it.

The schema is as strict as the sample. Loosen it where real data varies, such as a string field that can also be empty.

Ctrl+Enter or ⌘+Enter runs this tool immediately.

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JSON sample

Zod schema

Waiting for input.

Parsing stays in this browser. Input is not uploaded or saved.

Paste a JSON response, request body, or form payload, or load the sample.
Read the schemas. Each nested object gets its own named schema, followed by a type made with z.infer.
Copy the file, then add refinements such as .email() or .min(1) that a sample cannot show.

Whole numbers become z.number().int(). If the field can hold decimals, remove .int().
Strings become z.string(). Formats such as email, URL, or date are not detected.
A key missing from some array items becomes .optional(). A value that is null in some items becomes .nullable().
A field that is only null becomes z.null(). Replace it with the real type and .nullable().
An empty array becomes z.array(z.unknown()).

trusted appears in one session, so it becomes trusted: z.boolean().optional().

{"sessions": [{"device": "a"}, {"device": "b", "trusted": true}]}

An array of numbers and null becomes z.array(z.number().int().nullable()).

{"scores": [3, null, 5]}

Expected double-quoted property name: The sample is not strict JSON. Remove trailing commas and comments first.

Which Zod version does this target?: The output uses z.object, z.array, z.union, .optional(), .nullable(), and z.infer, which work the same in Zod 3 and Zod 4.
Why is each schema followed by a type?: z.infer gives you the TypeScript type from the schema, so the validator and the type cannot drift apart.
Is the JSON uploaded?: No. The schema is generated in your browser.

JSON to TypeScript converter
Generate TypeScript interfaces from a JSON sample in the browser. Array items are merged, and keys missing from some items become optional.
JSON Schema generator
Generate a draft 2020-12 JSON Schema from a JSON sample in the browser. Types, nested objects, array items, and required keys are inferred.
JSON Schema validator
Check a JSON document against a JSON Schema in the browser. Draft-07 and 2020-12 are supported, and remote $ref values are not fetched.