Deluge is a full-featured BitTorrent client for Linux, OS X, Unix and Windows.
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BitTornado is a Free cross-platform BitTorrent client.
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Flush is GTK-based BitTorrent client for linux similar to utorrent.
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qBittorrent is a lightweight but featureful BitTorrent client that is multi-platform and very easy to use.
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Halite is an open-source BitTorrent client and is based on the excellent libtorrent library from Rasterbar Software.
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Transmission is a cross-platform BitTorrent client that is Free and Community-Driven.
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