Lightweight bittorrent tracker contained in a single PHP file
BitStorm was originally written by Peter Caprioli as a lightweight bittorrent tracker contained in a single PHP file. As it used only a single flat file as a database, it had difficulty scaling past ~10 announces per second.
Peter created a fork of his project to add MySQL support, allowing it to scale. In 2011, Josh Duff made some changes to allow more efficient use of the database, and further scaling.
BitStorm: a very light bittorrent tracker that anyone can install!