1. Simple, efficient background processing for Ruby.

  2. Microsoft Azure Service Bus offers cloud messaging service between applications and services.

  3. RabbitMQ is an open source message broker software.

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

  5. Scalable MQTT message broker.

  6. CloudMQTT implements MQ Telemetry Transport protocol for carrying out messaging using a publish/subscribe message queueing model.

  7. Eclipse Paho project provides open-source client implementations of MQTT and MQTT-SN messaging protocols.

  8. Realtime Messaging is a cloud based message broker. Enabling developers to build cross-platform apps that require realtime communication

  9. Resque is a Redis-backed Ruby library for creating background jobs, placing them on multiple queues, and processing them later.

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

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

  12. Google Cloud Messaging is a service that enables developers to send data from servers to both Android applications or Chrome apps.