Google App Engine - A powerful platform to build web and mobile apps that scale automatically.
Clever Cloud - Clever Cloud helps developers deploy and run their apps with bulletproof infrastructure, automatic scaling, fair pricing and other cool features.
Pivotal - Pivotal Software provides enterprise PaaS-based solutions.
Heroku - Agile deployment platform for Ruby, Node.js, Clojure, Java, Python, and Scala. Setup takes only minutes and deploys are instant through git. Leave tedious server maintenance to Heroku and focus on your code.
DigitalOcean - Simplifying cloud hosting. Deploy an SSD cloud server in 55 seconds.
Dokku - Docker powered mini-Heroku in around 100 lines of Bash