What is Open Source?
Open Atrium is completely open source. Why? Because for Open Atrium to be one of the best collaboration tools out there, the teams using it need to have full control over how it works.
Open Atrium's code base is GPL v. 2, inherited from Drupal, the open source platform that's the backbone of the package.
For those who are new to open source, the story goes something like this. In what is seen as the most productive reaction in history to being pissed off at an office printer, Richard Stallman started the free software movement (among other things) to promote the right for people to be able to modify software, rather than be stuck with proprietary software with restrictive licensing.
Drupal is an open source content management framework that's easy to modify and has a user base of hundreds of thousands of people. The very active community has an estimated 240,000 websites powered by Drupal 6. Open Atrium is one, being built on Drupal 6 core. Drupal 7 was released in January of 2011, and we are encouraging community members to participate in upgrading Open Atrium to Drupal 7, visit community.openatrium.com/dev to see how you can help.