rtorrent is a BitTorrent client for ncurses, using the libtorrent library. The client and library is written in C++ with emphasis on speed and efficiency, while delivering equivalent features to those found in GUI based clients in an ncurses client.
LibTorrent is a BitTorrent library written in C++ for *nix, with a focus on high performance and good code. The library differentiates itself from other implementations by transfering directly from file pages to the network stack. On high-bandwidth connections it is able to seed at 3 times the speed of the official client.