Neo Technology, the sponsor company of the graph database Neo4j, has released the Community Edition of Neo4j under a GNU General Public License (GPL). Previously, it was available under the Affero General Public License.
"That means that in every scenario where you can use MySQL for free, you can now also use Neo4j Community for free," writes Neo Technology co-founder Emil Eifrem on his blog.
According to Wikipedia, the Affero General Public License was "designed to close a perceived application service provider "loophole" (the "ASP loophole") in the ordinary GPL, whereby using but not distributing the software, the copyleft provisions are not triggered." What this should mean in practice is that companies will now be able to provide hosted services based on Neo4j without open-sourcing code modifications or paying for the commercial version of Neo4j (Disclaimer: This does not constitute legal advice. Please consult your legal counsel if you have questions regarding open source licenses.)
Interest in graph databases in general, and Neo4j in particular, has been growing for the year. Eifrem writes "Some developers found the Neo4j license too restrictive, preventing their teams from using Neo4j." Eifrem believes this new, less restrictive license will spur more growth in the graph database sector.
"Since the graph data model is the richest of all the NOSQL data models, graph databases have the opportunity to be the most useful for most people in most situations, and ultimately grab the largest slice of the NOSQL market," Eifrem writes.