FreeSim is a fully-customizable macroscopic and microscopic free-flow traffic simulator developed by Dr. Jeffrey Miller at the University of Alaska, Anchorage, and as part of his Ph.D. dissertation at the University of Southern California under the advisement of Professor Ellis Horowitz. FreeSim allows for multiple freeway systems to be easily represented and loaded into the simulator as a graph data structure with edge weights determined by the current speeds. Traffic and graph algorithms can be created and executed for the entire network or for individual vehicles or nodes, and the traffic data used by the simulator can be user-generated or be converted from real-time data gathered by a transportation organization. The vehicles in FreeSim can communicate with the system monitoring the traffic on the freeways, which makes FreeSim ideal for Intelligent Transportation System simulation. FreeSim is licensed under the GNU General Public License, and the source code is available for download. There is also a demo of FreeSim that can be run through a browser.