Trello - Infinitely flexible. Incredibly easy to use. Great mobile apps. It's free. Trello keeps track of everything, from the big picture to the minute details.
Jenkins - Jenkins is an open-source continuous integration server with 300+ plugins to support all kinds of software development
KanbanFlow - KanbanFlow is a Lean project management tool allowing real-time collaboration between team members. Supports the Pomodoro technique for time tracking.
CircleCI - CircleCI gives web developers powerful Continuous Integration and Deployment with easy setup and maintenance.
Meistertask - MeisterTask is an intuitive task management and collaboration tool.
Travis CI - Focus on writing code. Let Travis CI take care of running your tests and deploying your apps.