1) confirmation URL (from email) is not "usual": http://siteguardian.dev:443/users/confirm/MKdwDZZubTqIs6Lz...
The correct form will be: https://.. (and without port)
2) After login I have: 302 redirect to http://app.siteguardian.local:4000
Good luck! :)
1) I added the same domains. I think, you can validates uniqueness for user scope.
2) I added more than 2 domains (only 2 available in free tariff).
I also appreciate the effort trying to break the app :D