What are some alternatives?
When comparing twitter.github.io Kestrel and IronMQ, you can also consider the following products
nginx - A high performance free open source web server powering busiest sites on the Internet.
Apache Kafka - Apache Kafka is an open-source message broker project developed by the Apache Software Foundation written in Scala.
CloudAMQP - CloudAMQP automates every part of setup, running and scaling of RabbitMQ clusters. Available on all major cloud and application platforms.
Xplenty - Xplenty gives you the power of Hadoop data processing without the need for installing hardware or software, and without the need for Hadoop programming skills.It's all in the cloud.
RabbitMQ - RabbitMQ is an open source message broker software.
Cyclr - Powerful SaaS integration toolkit for SaaS developers - create, amplify, manage and publish native integrations from within your app.