Looking at the scripts that Codeforces is loading, I found that it is using Evercookie. Evercookie is a script written by Samy Kamkar (the same guy who created Samy worm) which creates "supercookies", pieces of information that a website can store on the user's machine that are intentionally made difficult to get rid of. Supercookies are generally used for tracking, and the use of such technology would be understandable for an anti-privacy company such as Facebook, but why is Codeforces doing this?