The qBittorrent project aims to provide a Free Software alternative to µTorrent. Additionally, qBittorrent runs and provides the same features on all major platforms (Linux, Mac OS X, Windows, OS/2, FreeBSD).
qBittorrent is based on the Qt toolkit and libtorrent-rasterbar library.
Polished µTorrent-like User Interface
Well-integrated and extensible Search Engine
Simultaneous search in most famous BitTorrent search sites
Per-category-specific search requests (e.g. Books, Music, Movies)
All Bittorrent extensions
DHT, Peer Exchange, Full encryption, Magnet/BitComet URIs, ...
Remote control through a Web user interface
Nearly identical to the regular UI, all in Ajax
Advanced control over trackers, peers and torrents
Torrents queueing and prioritizing
Torrent content selection and prioritizing
Natively integrated: When Downloads Completes Options (no need for additional script or plug-in)
Exit, Suspend, Hibernate, Shutdown
UPnP / NAT-PMP port forwarding support
Available in ~41 languages (Unicode support)
Torrent creation tool
Advanced RSS support with download filters (inc. regex)
IP Filtering (eMule and PeerGuardian compatible)
Sequential downloading (aka "Download in order")
Available on most platforms: Linux, Mac OS X, Windows, OS/2, FreeBSD