Copyright Ken Stephenson, University of Tennessee, Knoxville. CirclePack-Jxx.jar is a Java program for creation, manipulation, analysis, and visualization of circle packings. It should run on all platforms with a simple double click from the desktop or from a terminal with the command "java -jar CirclePack-Jxx.jar". The Java source code is available in cpcore-source-Jxx.jar. CirclePack operates most effectively via "scripts", as illustrated by those *.xmd files in the script directory. CirclePack versions starting with J5.0 mark a major revision in managing combinatorics within the code, and this will interfere with the running of some script. The software requires Java 1.6 or later. If you are running MacOS, be sure that Java 1.6+ is installed and also is at the top of the Java run list.