RabbitMQ

RabbitMQ is an open-source message broker that also supports streaming. Applications publish messages to the broker and other applications consume them, which lets services communicate without depending on each other being available at the same moment. This repository contains the core server and the built-in tier 1 plugins.

The broker speaks several protocols: AMQP 0-9-1, AMQP 1.0, its own Stream Protocol, MQTT versions 3.1, 3.1.1 and 5.0, STOMP 1.0 through 1.2, and MQTT and STOMP over WebSocket. Quorum queues provide replicated, consistency-oriented queues, while streams offer a persistent, replicated append-only log that consumers can read without removing messages. Monitoring works with Prometheus and Grafana.

The server is licensed under the MPL 2.0 and can be installed on many platforms, with a Kubernetes Cluster Operator for container deployments. The documentation includes tutorials, a production checklist and clustering guides. Commercial editions and paid support from Broadcom exist alongside the community edition, which is supported through GitHub Discussions and Discord.