ifconfig.me is a similar service which I often use. It has a nice feature that if you do "curl ifconfig.me", you'll get only a string with the ip address, no markup.
On a Reddit post, someone mentioned ip.wtf that they created as a similar service. Aside from using it in a browser, it also provides a single IP address with curl ip.wtf, with less typing. I also like getting more information by using this: curl --json "" ip.wtf
