Deluge

Deluge is a BitTorrent client built around a daemon and a separate interface. The daemon holds the torrents and does the transferring; a GTK desktop window, a web page or a console client attaches to it. That split means the daemon can keep running on a home server or a NAS while you connect from a laptop, and closing the window does not stop the downloads.

Most of what Deluge does beyond the basics comes from plugins that ship with it: scheduling bandwidth by hour, moving finished files to another folder, applying labels, or exposing statistics. Bandwidth limits can be set globally or per torrent, and the queue decides how many transfers run at once.

The project is written in Python and packaged for Linux, Windows and macOS, though the daemon-plus-thin-client arrangement is the reason most people pick it.