Its a perlscript.

OTD One Time Download
Current version:
otd-1.72.tar.gz

Old releases:
otd-1.71.tar.gz
otd-1.7.tar.gz
otd-1.6.tar.gz
otd-1.5.tar.gz
otd-1.4.tar.gz
otd-1.3.tar.gz
otd-1.2.tar.gz
otd-1.1.tar.gz
otd-1.0.tar.gz

Thomas Karlsson otd at relea.se
Screenshot of the administration
Screenshot of the userinterface

The documentation is here.