Gantt - Create beautiful Gantt charts
openDesktop.org - The website openDesktop.
GoodGantt - The best Gantt chart for Trello®
SourceForge - The Complete Open-Source and Business Software Platform.
GANTTplanner - Turn your Google Calendar into a Gantt chart
Freecode - Freecode (formerly known as Freshmeat) is one of the legit open source development platforms that will be the key for developers and programmers to have a streamlined process via having enhanced collaboration and coding leverages.