Other Dark- and Experimental Overlay Networks

• Tor (The onion router) is an anonymity network that also features a darknet - its "hidden services". It's the most popular instance of a darknet.[1]
• I2P (Invisible Internet Project) is another overlay network that features a darknet whose sites are called "Eepsites".
• Freenet is a popular darknet (friend-to-friend) by default; since version 0.7 it can run as a "opennet" (connecting to untrusted users).
• RetroShare can be run as a darknet (friend-to-friend) by default to perform anonymous file transfers if DHT and Discovery features are disabled.
• GNUnet is a darknet if the "F2F (network) topology" option is enabled.
• Syndie is software used to publish distributed forums over the anonymous networks of I2P, Tor and Freenet. OneSwarm can be run as a darknet for friend-to-friend file-sharing.
• Tribler can be run as a darknet for file-sharing.
• Netsukuku
• Agora ?
• ChaosVPN
• Freifunk