# UnionSchemaAsync

> This document is the Markdown version of [valibot.dev/api/UnionSchemaAsync/](https://valibot.dev/api/UnionSchemaAsync/). For the complete documentation index, see [llms.txt](https://valibot.dev/llms.txt).

Union schema async interface.

## Generics

- `TOptions` `extends UnionOptionsAsync`
- `TMessage` `extends ErrorMessage<UnionIssue<InferIssue<TOptions[number]>>> | undefined`

## Definition

- `UnionSchemaAsync` `BaseSchemaAsync<InferInput<TOptions[number]>, InferOutput<TOptions[number]>, UnionIssue<InferIssue<TOptions[number]>> | InferIssue<TOptions[number]>>`
  - `type` `'union'`
  - `reference` `typeof union | typeof unionAsync`
  - `options` `TOptions`
  - `message` `TMessage`