Transmission

Transmission is a BitTorrent client designed to stay out of the way. It is split into a background daemon that does the transferring and several front ends that drive it: GTK and Qt desktop interfaces, a web interface served over HTTP, and a command-line remote. Downloads therefore keep running whether or not a window is open, which is what makes it a common choice on headless machines.

It handles torrent files and magnet links, and supports the distributed hash table, peer exchange and local peer discovery for finding peers without relying on a tracker. Individual files inside a torrent can be deselected or given a different priority. A watch directory starts torrents automatically when a .torrent file lands in it, finished downloads can be moved to another folder, and a script can be run on completion.

Bandwidth control covers global and per-torrent limits plus an alternate, lower set that can be switched on by hand or on a daily schedule. Peer blocklists load from a URL and refresh automatically. The daemon is reached over an RPC interface with optional password authentication.