AsyncAPI
The specification standard for async, event-driven APIs over Kafka, MQTT, WebSockets, and more — the async equivalent of OpenAPI. The ecosystem includes CLI, parser, code generators, and server stub templates. Widely adopted in microservices and streaming architectures.
Redocly
Combines Redoc (25k+ GitHub stars) with a powerful CLI for linting, validating, and bundling OpenAPI specs. Supports OpenAPI 3.x, Swagger 2.0, AsyncAPI, and Arazzo. Enterprise offering adds developer portals and auto-generated code samples across teams.