AsyncAPI — OpenAPI for Event-Driven Architectures

OpenAPI for REST — but what about Kafka topics and event-driven communication? AsyncAPI fills this gap — a standard specification for asynchronous APIs.

The Problem: Undocumented Events¶

After a year of event-driven architecture, we have 40 Kafka topics. Who writes to them? What’s the message format? What does the “status” field mean? Tribal knowledge — and a new developer is lost.

AsyncAPI Specification¶

A YAML file describing channels (topics), message schemas, server info, and security. Auto-generated documentation, JSON Schema validation, and code generation for both producers and consumers.

Schema Registry + AsyncAPI¶

Confluent Schema Registry enforces Avro schemas. The AsyncAPI specification references these schemas. Result: schema evolution is controlled, breaking changes are detected in CI.

Document Your Events¶

AsyncAPI is to event-driven what OpenAPI is to REST. The contract-first approach works for asynchronous communication too.