# OpenAPI Callbacks

You could create an API with a *path operation* that could trigger a request to an *external API* created by someone else (probably the same developer that would be *using* your API).

!!! tip
    Note that we're using async/await with the new `AsyncClient` - the request is asynchronous.

!!! warning
    If your application relies on lifespan events, the `AsyncClient` won't trigger these events. To ensure they are triggered, use `LifespanManager` from <a href="https://github.com/florimondmanca/asgi-lifespan#usage" class="external-link" target="_blank">florimondmanca/asgi-lifespan</a>.