Torrent clients

Fragments – free and open source, easy to use BitTorrent client for GNOME desktop graphic environment

Rats on The Boat – free and open source BitTorrent P2P multi-platform search engine for Desktop with integrated torrent client

Tribler is an free and open source software project facilitating searching, streaming and sharing content using P2P technology

WebTorrent Desktop is a free and open source streaming torrent client for the desktop

KTorrent – free and open source BitTorrent client by KDE. It allows you to run multiple torrents at the same time and its features can be extended by plugins

qBittorrent – cross-platform free and open source software alternative to µTorrent. BitTorrent file sharing network client. Torrent client with a built-in search engine