AsyncAPI does for messages and events what OpenAPI does for HTTP request-response: gives you a machine-readable contract. It covers channels, messages, payload schemas, and protocol bindings across MQTT, AMQP, WebSockets, STOMP, Kafka, NATS, Redis and more.
You need it as soon as anyone outside the producing team depends on an event. Right now, in most organizations, the answer to “what messages does this topic carry and what is in them” is a person, a Confluence page from 2021, or a sample payload someone pasted into Slack. That is precisely the state HTTP APIs were in before OpenAPI, and it has all the same consequences: no generated documentation, no validation, no discovery, no contract testing, no way to know who consumes what.
I have consistently treated AsyncAPI adoption as a leading indicator of how mature an organization’s API operations really are, because it means the event-driven estate is being held to the same standard as the HTTP estate rather than growing up in the dark.
It is also one of the more healthily run specifications in the space, with a genuinely open community. And the two worlds connect properly — OpenAPI functions as the HTTP binding within AsyncAPI, so this is not a competing universe you have to choose between.
