UMLet

First, get a Java 5 JRE, unless you did that already.

Linux
Now download the required version of UMLet from their website.

Extract the ZIP wherever you like.

You can start it like this: java -jar umlet.jar To have a more convenient way of starting it, create an executable file with the following content there: cd "`dirname "$0"`" java -jar umlet.jar $@ If you want a Desktop Entry too, create one named umlet.desktop with the following content (paths altered as necessary): [Desktop Entry] Name=UMLet Exec=/files/software/umlet/umlet Icon=/files/software/umlet/icons/umlet.gif Terminal=false Type=Application StartupNotify=true Categories=Development;Java
 * 1) !/bin/sh

Mac
It should be roughly the same than on Linux, feel free to elaborate here.