Get Website IP Address

Firefox Browser

Open Web Developer Tool (Ctrl+Shift+I) > Network (Ctrl+Shift+Q)
Select Net Tab
The website IP address can be seen in the Remote IP column
Refresh the page if necessary

Google Chrome Browser

Open Developer Tools > Network
Reload your page.
Select one of the URLs from the domain in question. 
The IP will be shown under Headers > General > Remote Address.

Linux Terminal with curl

  curl ipinfo.io/ip
  curl ipecho.net/plain ; echo
  curl ifconfig.me
  curl ipv4.icanhazip.com