Jenkins CI is the leading open-source continuous integration server. Built with Java, it provides over 400 plugins to support building and testing virtually any project.
Bamboo is Atlassian's continuous integration server as part of their suite of development tools.
CircleCI is a cloud-based continuous integration server that supports Ruby on Rails, Sinatra, Node, Python, PHP, Java and Clojure. It's a hosted solution designed to reduce as
Codeship is a fully customizable hosted CI platform.