Transmission - Transmission has the features you expect in a BitTorrent client: encryption, a web-based interface...

SABnzbd - SABnzbd is a free/open-source cross-platform binary newsreader written in Python.

BiglyBT - BiglyBT is a feature filled, open source, bittorrent client. Auto migrate from Vuze and Azureus. I2P integration, Swarm Merging, Advanced Tag System, WebTorrent support, built-in VPN kill switch, Meta-search, UPnP/DLNA access, and much more.

NZBGet - The most efficient usenet downloader.

Flush - GTK-based BitTorrent client.

GrabIt - GrabIt is a free application that enables you to easily find and download content from Usenet news...