Tools/RabbitMQ
RabbitMQ
Mature open-source message broker — queues plus flexible exchange types (direct, fanout, topic) for routing. The direct engine behind Amazon_MQ, and the most-used open-source alternative to Amazon_SQS (queueing) and Amazon_SNS (fanout exchange ≈ pub/sub). ActiveMQ is the other engine Amazon MQ manages, more common in legacy Java/JMS shops.