RSMQ

A lightweight message queue for Node.js that requires a Redis server.

Amazon SQS

Amazon Simple Queue Service is a fully managed message queuing service.

Job queue for Android to easily schedule jobs that run in the background, improving UX and application stability.

Apache Kafka is an open-source message broker project developed by the Apache Software Foundation written in Scala.

Apache Qpid makes messaging tools that speak AMQP and support many languages and platforms.

Beanstalk is a simple, fast work queue.

CloudAMQP automates every part of setup, running and scaling of RabbitMQ clusters. Available on all major cloud and application platforms.

Real-time message streaming as a service. Powered by Apache Kafka. Fully managed, epic performance & superior support.

Simple pub/sub messaging for the web

Finagle is a protocol-agnostic RPC system.

Gearman provides a generic application framework to farm out work to other machines or processes that are better suited to do the work.

IronWorker is a task processor for applications that isolates the code and dependencies of individual tasks to be processed on demand.

A realtime distributed messaging platform.

RabbitMQ is an open source message broker software.

VerneMQ is an open source, high-performance, clusterable MQTT broker.

ZeroMQ is a high-performance asynchronous messaging library.