WP Project Manager is a web based project management software for WordPress with frontend feature. It is completely open source. So you can customize it exactly the way you want. It also has file sharing, task list, calendar, milestone, private messaging and discussion features. It also has some add-on to enhance more functionality.
v1.3 – September 3, 2015
* [improved] Free/Pro separation. Massive code change
* [improved] Email notification templates updated. Removed the settings from admin.