JAR is a tool for creating compressed filearchives that use .j as their file extension. It was invented by Robert K. Jung and was meant to be a successor to ARJ. It can achieve very good compression, but is not in wide use. JAR should not be confused with the .jar file extension used for Java Archive files, which are actually zip files with some embedded metadata.
One internal license costs $45 and 2-10 licenses for non-company use cost $15 per computer. However, the price per computer decreases as more licenses are purchased.