To Be Permissive Or Not To Be Permissive, That Is The Question For Open Source Licensors

A new study of open source project growth suggests that choosing a permissive license can help your community to grow faster

The production of open source software continues to grow at a good pace. Of course, not all open source software is created equally, particularly when it comes to the license under which it’s offered. Different licenses impose different kinds of restrictions on what one can do with any derivative works created (e.g., can you charge money for something based on open source software?). License choice can, potentially, impact the growth of a community around a particular open source project. New research is now shedding some light on the effect of license choice on the growth of open source projects.

German researchers Gottfried Hoffmann, Dirk Riehle, Carsten Kolassa and Wolfgang Mauerer recently set out to examine the relationship between open source license choice and project growth and their results were recently published in the paper “A Dual Model of Open Source License Growth”. They looked at data obtained from Ohloh.net (now Black Duck Open Hub) on over 5,000 open source projects active between 1995 through June, 2007. Their goal was to explore the effect of choosing more “restrictive” open source licenses versus more “permissive” licenses.

Restrictive licenses were defined as those that required derivative works to be released under the same license, such as the GNU General Public License (AKA GPL, copyleft) and CC-BY-SA. Permissive licenses, on the other hand, were defined as those that let licensees do what they want with the resulting work, including selling it. Permissive licenses include the MIT, BSD, Apache, Python and public domain licenses...