The project management system itself has already set and it's easy to pick up

I've used the free solution for many of my projects. The product allows you to choose between scrum or kanban styles of organization. It's beautiful, easy to use, and doesn't seem to have any bugs.

The Kanban board is excellent for tracking feature development status. Moving tickets is fun and easy to do and the custom fields is a more convenient way for our billing purposes. Kanban page has a progress bar/indicator informing clients of the progress of certain task.