SABnzbd - SABnzbd is a free/open-source cross-platform binary newsreader written in Python.
rTorrent - rtorrent is a BitTorrent client for ncurses, using the libtorrent library.
NZBGet - The most efficient usenet downloader.
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.
GrabIt - GrabIt is a free application that enables you to easily find and download content from Usenet news...
qBittorrent - Lightweight and open source torrent client that runs on all major platforms.