RabbitMQ

RabbitMQ is the most widely deployed open-source message broker, implementing AMQP protocol for reliable async communication between services. It supports multiple messaging patterns: pub/sub, routing, topics, and RPC. Its management UI, plugin ecosystem, and mature tooling make it a practical choice for most microservice architectures. RabbitMQ excels at task queues, event distribution, and decoupling services. While Kafka is preferred for high-throughput streaming, RabbitMQ wins for traditional messaging with complex routing, message acknowledgments, and dead-letter handling.