ActiveMQ

Open source multi-protocol Java-based message broker supporting industry standard protocols including AMQP, STOMP, MQTT, and JMS. Provides high availability through shared storage and network of brokers for load distribution. Supports Jakarta Messaging 3.1 and JMS 2.0 with full JMS 1.1 compatibility. Offers flexible deployment options including standalone processes or embedded within applications. Includes Apache Camel integration for enterprise integration patterns.