One of them used to be robtex.com [1] but now they require a login to see most info. The same has happened to most other useful utility sites. Once they get popular they require logins. Most of the time I just use the command line tool whois. This should be available on Mac and if it isn't in Windows I assume it could be installed via WSL or Cygwin.
[1] - https://www.robtex.com/