Amazon AWS - Amazon Web Services offers reliable, scalable, and inexpensive cloud computing services. Free to join, pay only for what you use.
Google App Engine - A powerful platform to build web and mobile apps that scale automatically.
IBM Bluemix - IBM Bluemix is an open-standard, cloud-based platform that enables users to build, manage, and run apps on mobile, web, and smart devices.
Dokku - Docker powered mini-Heroku in around 100 lines of Bash
Microsoft Cloud Platform - Microsoft approaches cloud computing as a way to help customers take a key step toward better business agility, economics, and user experiences.
Google Cloud Functions - A serverless platform for building event-based microservices.