This post contains a small handful of distinct services to query your machine external IP address.
URL: https://www.google.com/search?q=what+is+my+ip
As of this writing, this doesn’t work on duckduckgo: https://duckduckgo.com/?q=what+is+my+ip. I suppose this is related to their philosophy of not tracking their users.
This is the easiest method when you have a web browser as you do not need to memorize any URL.
I can haz ip
$ curl icanhazip.com
NNN.NNN.NNN.NNN
I love the simplicity of I can haz ip. It just returns your IP address in plain text, nothing else. It also works from the web browser. You can find details about it here. TL;DR: It was an open source pet project of a single person (Major Hayden), then it was eventually bought by Cloudflare as it immensely grew.
It’s also possible to query your IPv6 address in case you have one:
$ curl -6 icanhazip.com
IPInfo
URL: https://ipinfo.io/
IPInfo returns structured data beyond just your IP address. There are several similar services that do this, for example, What is my IP? and https://ifconfig.co/, however IPInfo is the cleanest one I have seen.
ping.eu
URL: https://ping.eu/
I’ll also give an honourable mention to ping.eu as it contains a small handful of utilities to check for things like Traceroute, DNS, whois, port check, etc.