The @orpc/arktype package provides an ArkType-to-JSON Schema converter for oRPC’s OpenAPI generator. Like the Valibot converter, it is marked as experimental_ as ArkType’s JSON Schema export API continues to mature.
Installation
npm install @orpc/arktype arktype
Usage
import { OpenAPIGenerator } from '@orpc/openapi'
import { experimental_ArkTypeToJsonSchemaConverter } from '@orpc/arktype'
import { type } from 'arktype'
import { os } from '@orpc/server'
const generator = new OpenAPIGenerator({
schemaConverters: [new experimental_ArkTypeToJsonSchemaConverter()],
})
const PlanetSchema = type({
id: 'number',
name: 'string',
'description?': 'string',
})
const router = {
planet: {
find: os
.input(type({ id: 'number' }))
.output(PlanetSchema)
.handler(async ({ input }) => ({ id: input.id, name: 'Earth' })),
},
}
const spec = await generator.generate(router, {
info: { title: 'Planet API', version: '1.0.0' },
})
Constructor options
class experimental_ArkTypeToJsonSchemaConverter implements ConditionalSchemaConverter {
constructor(options?: ToJsonSchema.Options)
}
Type.toJsonSchema(). The converter applies a sensible default fallback for Date types, rendering them as { type: 'string', format: 'date-time' }:
const defaultFallback = {
date: (ctx) => ({
...ctx.base,
type: 'string',
format: 'date-time',
}),
}
fallback option:
new experimental_ArkTypeToJsonSchemaConverter({
fallback: {
date: (ctx) => ({ type: 'string', format: 'date' }),
},
})
Mixing ArkType with other libraries
import { OpenAPIGenerator } from '@orpc/openapi'
import { ZodToJsonSchemaConverter } from '@orpc/zod/zod4'
import { experimental_ArkTypeToJsonSchemaConverter } from '@orpc/arktype'
const generator = new OpenAPIGenerator({
schemaConverters: [
new ZodToJsonSchemaConverter(),
new experimental_ArkTypeToJsonSchemaConverter(),
],
})
~standard.vendor property. ArkType schemas have vendor === 'arktype', so they’re automatically routed to experimental_ArkTypeToJsonSchemaConverter.
The experimental_ prefix reflects that ArkType’s toJsonSchema() API is still evolving. The interface may change in future releases.
Notes on strategy
Unlike the Zod converter, the ArkType converter does not currently differentiate between input and output strategies — it always calls schema.toJsonSchema(options) with the same options regardless of strategy. If your ArkType schemas transform data between input and output, the generated spec may not reflect the transformation. 