HeySpace - HeySpace is the only free task and simple project management software with communication and collaboration feature.
Jenkins - Jenkins is an open-source continuous integration server with 300+ plugins to support all kinds of software development
P2 - Share, discuss, and collab with your team. By Wordpress.
CircleCI - CircleCI gives web developers powerful Continuous Integration and Deployment with easy setup and maintenance.
Slack - A messaging app for teams who see through the Earth!
Travis CI - Focus on writing code. Let Travis CI take care of running your tests and deploying your apps.