opentracker from Dirk Engling powered one of the biggest BitTorrent trackers,
The Pirate Bay tracker.
 is a high performance open source tracker designed to run on
Google App Engine.
 is a small tracker written in PHP which does not require a database server and runs on any PHP compatible web server.
BitStorm 2 uses a
MySQL database instead of
flat file to improve scalability.
 is an open source, commercially supported tracker with integrated web-based management portal.
 is a standalone BitTorrent tracker written in C++, under the MIT license.
 is a BitTorrent tracker written in C++ for the Gazelle