O P2P ou Peer-to-Peer(Par-a-Par) no bruto é uma tecnologia para estabelecer uma espécie de rede de computadores virtual, onde cada estação possui capacidades e responsabilidades equivalentes. Difere da arquitetura cliente/servidor, no qual alguns computadores são dedicados a servirem dados a outros. Esta definição, porém, ainda é demasiado sucinta para representar todos os significados do termo Peer-to-Peer.

Aplicativos multi-redes

• DreaMule (eDonkey, Kad (rede)) (Windows, Linux)
• aMule (eDonkey, Kad (rede)) (Linux, Mac OS X, FreeBSD, NetBSD, OpenBSD, Windows e Solaris Operating Environment) (software livre)
• eMule (eDonkey, Kad (rede)) (Windows) (software livre)
• FileScope (Gnutella, Gnutella2, eDonkey, OpenNap) (multiplataforma) (open source)
• giFT (own OpenFT protocol, and with plugins - FastTrack, eDonkey e Gnutella) (open source)
• Gnucleus (Gnutella, Gnutella2) (Windows) (open source)
• iMesh (Fasttrack, eDonkey, Gnutella, Gnutella2) (Microsoft Windows) (closed source)
• KCeasy (Ares, FastTrack (plugin required), Gnutella, OpenFT) (open source)
• Kiwi Alpha (Gnutella, Gnutella2) (Windows) (closed source)
• MLDonkey (BitTorrent, eDonkey, FastTrack, Gnutella, Gnutella2, Kademlia) (Windows, Linux, Mac OS X) (open source)
• Morpheus (NEO Network, Gnutella, Gnutella2, BitTorrent) (Windows) (closed source)
• Napshare (MUTE, Key Network) (Linux, Windows) (open source)
• Shareaza (BitTorrent, eDonkey, Gnutella, Gnutella2) (Windows) (open source)
• WinMX (Windows) (closed source)
• Zultrax (Gnutella, ZEPP) (Windows) (closed source)