Nifty - Manage projects, work, and communications in one place.
Scrumpy - A simple, beautiful and agile project management software
Intercom on Product Management - The ultimate resource for aspiring product managers
Codegiant - Codegiant - Issue tracking, git repositories, continuous integration and documentation in a single platform.
GitHub Project Management - No-fluff guide to building a collaborative development team
UpDiagram - Free agile project management tool for scrum team