Standard OpenAPI

Standard Schema Validator's OpenAPI Schema Converter

Installation

Install the main package -

pnpm add @standard-community/standard-openapi

For some specific vendor, install the respective package also -

Vendor	Package
Zod v4	No additional package required
Zod v3	zod-openapi@4
Valibot	@valibot/to-json-schema

Zod

Zod v4 uses its built-in JSON Schema conversion, so it works without zod-openapi. To generate a reusable OpenAPI component, attach a ref with Zod metadata:

import z from "zod/v4";

const user = z.object({ id: z.string() }).meta({ ref: "User" });
const result = await toOpenAPISchema(user);

// result.schema is { $ref: "#/components/schemas/User" }
// result.components.schemas.User contains the object schema

Zod v3 requires zod-openapi@4; import zod-openapi/extend before using its .openapi() metadata method.

Usage

import * as v from "valibot";
import { toOpenAPISchema } from "@standard-community/standard-openapi";

// Define your schema
const schema = v.pipe(
    v.object({
        myString: v.string(),
        myUnion: v.union([v.number(), v.boolean()]),
    }),
    v.description("My neat object schema"),
);

// Convert it to OpenAPI Schema
const openapiSchema = await toOpenAPISchema(schema);

Sync Usage

Adding support for Unsupported validation libs

import { toOpenAPISchema, loadVendor } from "@standard-community/standard-openapi";
import { convertSchemaToJson } from "your-validation-lib";

// The lib should support Standard Schema, like Sury
// as we use 'schema["~standard"].vendor' to get the vendor name
// Eg. loadVendor(zod["~standard"].vendor, convertorFunction)
loadVendor("validation-lib-name", convertSchemaToJson)

// Define your validation schema
const schema = {
    // ...
};

// Convert it to OpenAPI Schema
const openapiSchema = toOpenAPISchema(schema);

Customize the toOpenAPISchema of a supported lib

import { z } from "zod/v4";
import { toJSONSchema } from "zod/v4/core";
import { toOpenAPISchema, loadVendor } from "@standard-community/standard-openapi";
import { convertToOpenAPISchema } from "@standard-community/standard-openapi/convert";

// Or pass a custom implmentation
loadVendor("zod", (schema, context) => {
    return convertToOpenAPISchema(toJSONSchema(schema, {
        io: "input"
    }), context);
})

// Define your schema
const schema = z.object({
    myString: z.string(),
    myUnion: z.union([z.number(), z.boolean()]),
}),

// Convert it to OpenAPI Schema
const openapiSchema = await toOpenAPISchema(schema);