Mullvad is one of the few VPN providers that offers multiple exit IPs for its servers. If two people connect to the same server, they will usually end up with different public IPs. With only 578 servers (compared to Proton VPN’s 20,000 ), this kind of vertical scaling makes sense to avoid cramming too many users onto one IP, which would be a problem on sites with overzealous IP blocks and ratelimits. Surprisingly, the exit IP you are given is not randomized each time you connect to the server, but deterministically picked based on your WireGuard key , which rotates every 1 to 30 days (unless you use a third-party client, in which case it never rotates). But wait.. if each server assigns you an independently picked static exit IP, wouldn’t just a few of those be enough to uniquely identify you among every other Mullvad user? Putting it to the test I wrote a script that repeatedly changes my pubkey and fetches exit IPs for a set of 9 servers.…