rTorrent is described as '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' and is a popular Torrent Client in the file sharing category. There are more than 50 alternatives to rTorrent for a variety of platforms, including Windows, Linux, Mac, Android and BSD apps. The best rTorrent alternative is qBittorrent, which is both free and Open Source. Other great apps like rTorrent are Transmission, µTorrent, Deluge and aria2.
NTorrent is a GUI for rTorrent.