There's also https://keys.pub/ (from someone ex-Keybase, if I remember correctly). I haven't looked at either closely. Can anyone compare and contrast?
One thing is that I don't see anything about auditing for Keyoxide, but Keys is up-front with a warning.
The only reasonable attack vector I can see is hijacking the website (or proxy server) to return different keys or show something is verified when it's actually not.