It's a "virtual lan" project like hamachi or (some configurations of) openvpn. Sometimes you want two computers to be able to talk to one another, even if the

It's a "virtual lan" project like hamachi or (some configurations of) openvpn. Sometimes you want two computers to be able to talk to one another, even if they're behind a NAT or there's otherwise infrastructure between them that makes this difficult. Zerotier makes that easier by * Checking to see if the other device is directly reachable, if you're both already on the same LAN. * Employing NAT hole punching to try to establish a path anyway * Finally proxying the connection over a server reachable by both In my experience it's the easiest way to make sure all my computers are reachable, even if one of those computers is a phone and another one is behind a NAT.