RabbitMQ - RabbitMQ is an open source message broker software.
Raygun - Raygun gives developers meaningful insights into problems affecting their applications. Discover issues - Understand the problem - Fix things faster.
ZeroMQ - ZeroMQ is a high-performance asynchronous messaging library.
Kafka - Apache Kafka is publish-subscribe messaging rethought as a distributed commit log.
D-Bus - D-Bus is a message bus system, a simple way for applications to talk to one another.
Sentry.io - From error tracking to performance monitoring, developers can see what actually matters, solve quicker, and learn continuously about their applications - from the frontend to the backend.