E621.net

e621.net is an image board mainly directed towards furry content of all kinds, largely being used for hosting pornography. It runs off of the Ouroboros platform, a software designed specifically for this site. Sister site source: e961.net e926.net

The name very likely comes from Monosodium Glutamate, a common food additive, which has an E number of 621 (Hence the name e621)