What are some alternatives?
Google App Engine - A powerful platform to build web and mobile apps that scale automatically.
Apache Kafka - Apache Kafka is an open-source message broker project developed by the Apache Software Foundation written in Scala.
Dokku - Docker powered mini-Heroku in around 100 lines of Bash
Amazon SQS - Amazon Simple Queue Service is a fully managed message queuing service.
Azure Web Apps - Create and deploy mission critical Web apps that scale with your business
Pusher - Pusher is a hosted API for quickly, easily and securely adding scalable realtime functionality via WebSockets to web and mobile apps.