Jenkins - Jenkins is an open-source continuous integration server with 300+ plugins to support all kinds of software development
HeySpace - HeySpace is the only free task and simple project management software with communication and collaboration feature.
CircleCI - CircleCI gives web developers powerful Continuous Integration and Deployment with easy setup and maintenance.
P2 - Share, discuss, and collab with your team. By Wordpress.
Codeship - Codeship is a fast and secure hosted Continuous Delivery platform that scales with your needs.
Slack - A messaging app for teams who see through the Earth!