Developer website: Gentleware
Poseidon for UML is a fully-fledged UML CASE tool. It evolved from the Open Source project ArgoUML and turns it to a world class modeling tool. With over 200.000 installations it belongs to the industries most important tools. The strong focus on usability makes it the easiest tool to learn and work with. It is delivered in different editions to meet different needs of different users.
Mac OS X 10.2 or later, JDK 1.3.1 or later