|Geektools Whois||(Others listed here have been discontinued in the meantime)|
The latest version gh 1.47 (Apr 11, 2021) is here to download.
You can either install it on your own site as above, or use it at the command prompt on any computer connected to Internet (and with Perl installed).
If all the above fails, here are some lists of Whois servers:
github.com (most up-to-date?)
("Historical" MIT March list (2000))