The Repast Suite is a family of free agent-based modeling libraries.
The Repast Suite is a family of advanced, free, and open source agent-based modeling and simulation platforms that have been under continuous development for over 20 years. Current source code and releases are hosted on Github https://repast.github.io/
Now part of Apache's Mahout machine learning project at http://mahout.apache.org/-- please see there for latest info and code and releases and support!