Here is the download link: http://x28hd.de/tool/dm.jar
(This is independent non-commercial software which will probably trigger a security warning. If in doubt, ask a friend to confirm that it is safe to run. We want you to be confident that this small program is absolutely innocent.)
See also:
The source code https://github.com/x28de/mytool
For the Java Runtime Environment (JRE), go to http://java.com
The extended version http://x28hd.de/tool/extended/extended.jar (equally free, but 4.4 MB)