Because any other "Whats my IP?"-tool sucks.
Try it here: https://ip.clerie.de
It's just one nginx site config. Feel free to host it yourself. It's open-source.
ip4.clerie.de and ip6.clerie.de just returns the remote addr.
ip4.clerie.de has only an A record. ip6.clerie.de has only an AAAA record.
If you want host this yourself you have to replace all hardcoded domains. You can use the following sed command. Don't forget to change
.EXAMPLE.COM to your own.
sed -e '/git.clerie.de/!s/.clerie.de/.EXAMPLE.COM/g;' ip.clerie.de
The first match is to exclude the line with the link to the git repo from replacing.