Zod to JSON Schema for OpenAPI

Why OpenAPI teams convert Zod

Zod is excellent inside TypeScript code, while OpenAPI needs schema objects that API docs, gateways, SDK generators, and external consumers can read. Converting Zod to JSON Schema lets a team keep Zod as the runtime source while publishing a portable contract; use the Zod to JSON Schema Converter when the immediate job is browser-based schema review.

Need full Zod to OpenAPI docs?

Use this page when you need component-level schema output. If your goal is a complete Swagger/OpenAPI document with paths, request bodies, responses, and package setup, use the dedicated Zod to OpenAPI guide.

Recommended FrameworkKit settings

Paste the inline Zod schema, set a schema name, then enable OpenAPI mode when nullable fields should be represented as OpenAPI 3.0 `nullable: true` output.

• Use OpenAPI mode for OpenAPI 3.0 documents.
• Use Draft 2020-12 or Draft 7 when the schema feeds a JSON Schema validator instead.
• Keep strict object handling on when extra keys should be rejected.
• Review transforms and refinements because executable logic cannot be represented in JSON Schema.

Example nullable output

A nullable Zod string becomes OpenAPI-compatible nullable schema output when OpenAPI mode is enabled.

const UserSchema = z.object({
  nickname: z.string().nullable(),
});

Where this fits in an OpenAPI document

FrameworkKit generates the schema object starter. Add that reviewed output under `components.schemas`, then wire it into request bodies, responses, or shared API component references.

{
  "openapi": "3.0.3",
  "components": {
    "schemas": {
      "User": {
        "type": "object",
        "properties": {
          "nickname": { "type": "string", "nullable": true }
        }
      }
    }
  }
}

Zod behavior OpenAPI cannot express

OpenAPI schema objects are data, not TypeScript code. Keep Zod-only runtime behavior in the application or model the closest portable constraint manually.

• Custom refine and superRefine callbacks need separate validation.
• Transforms and pipe output changes do not become OpenAPI schema behavior.
• Date, bigint, map, set, and custom schemas need JSON-friendly replacements.
• Coercion belongs in the application layer unless the API contract explicitly models the accepted input.

OpenAPI publishing checklist

Before publishing generated schema output, compare the Zod parser and the OpenAPI contract against the same fixture set.

• Test required, optional, nullable, and extra-property cases.
• Validate the final OpenAPI document with your docs or gateway tooling.
• Document whether Zod or OpenAPI is the long-term source of truth.
• Link reviewers back to the converter page so draft and OpenAPI mode choices are visible.

Zod to OpenAPI schema workflow

Use FrameworkKit to generate the starter code, then review the output before shipping it in production.

Zod to JSON Schema resources

FAQ

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