Extract domains only from a list of URLs

=== Extract domains only from a list of URLs ===

I am at best a slightly knowledgeable novice in regex, and I need some help with URLs.

I have a list of URLs in a LibreOffice Calc sheet that look like this:

http://www.localpetcare.com
https://app.clickfunnels.com/users/sign_in
https://www.timetopet.com/login#
https://www.bankatfirst.com/content/first-financial-bank/home/
https://app.truecoach.co/login
https://shield.mycoseva.com/qcoseva/ordernow.dhtml
https://d.comenity.net/as/authorization.oauth2?client_id=ngac


(These are part of a larger CSV dataset; thus the use of LibreOffice Calc.)

I need to strip out the protocol, any subdomains, and anything that occurs after the domain proper, so that the list will look like this:

localpetcare.com
clickfunnels.com
timetopet.com
bankatfirst.com
truecoach.co
mycoseva.com
comenity.net

Finding an expression that strips the protocol was easy. However, after a couple of days of online research, I can find nothing that will eliminate any arbitrary subdomain(s) and any text following the domain.

Any help gratefully accepted.
This problem will get thorny, some people—who no doubt know more than I do—recommend using a library or better yet, a browser's URL logic. You will encounter edge cases in the real world, for example your data set doesn't include invalid URLs nor the full set of possible characters in a domain name.

But given that it's fun to bang your head against problems and learn in the process, here's a regex that will extract the domain. There's only one capture group, $1. The parts of the URI that you don't care about are matched as non-capture groups with (?: opening each group. So obviously those could be capturing groups too if needed.

/^(?:https?:\/\/)(?:(?:www|ww\d)\.)?(?:(?:[^:/]+)\.)*([^:/]+\.[a-z0-9-]+)(?:\/.+)?$/

Mess around with it on regexr! hover over parts of the regex to see how they function
regexr.com/7mkbc
@TimRenner, thanks so much for this. I'll definitely check it out.

JGB