Disabling Output Validation

By default, oRPC validates procedure outputs against their defined schemas to ensure data consistency and type safety. If you only define output schemas for OpenAPI specification generation, you can disable output validation to improve performance.

Configuration

Set initialOutputValidationIndex to NaN in the $config method:

import { os } from '@orpc/server'

const base = os
  .$config({
    initialOutputValidationIndex: Number.NaN, 
  })

All procedures built from base will now have output validation disabled.

Limitation

This approach will not work correctly if your schema transforms the data into a different type during validation.

const procedure = base
  .output(z.object({ value: z.number().transform(val => String(val)) }))
  .handler(() => {
    return { value: 123 }
  })
  .callable()

const { value } = await procedure()

In this example, the client expects value to be a string, but because output validation is disabled, the transform logic is skipped. The client will receive a number instead, causing type mismatches.