Transmission is a BitTorrent client that is designed from the ground up to balance power with simplicity.

The initial preferences are set so that things "Just Work", while advanced features like watch directories, bad peer blocking, and the web interface can be configured with just a few clicks. With few dependencies and written in C, Transmission has a very low memory footprint. It's a good choice for low-memory hardware. Unlike some cross-platform programs, Transmission seamlessly integrates with your operating system. The Mac OS X interface is written in Objective-C and uses Growl notifications and dock badging to keep you informed. Transmission has the features you expect in a BitTorrent client: encryption, a web-based interface, peer exchange, UPnP and NAT-PMP port forwarding, web seed support, watch directories, tracker editing, global and per-torrent speed limits, and more.