IP Guide - Look up IP addresses, networks, and ASNs
Nessus - Nessus Professional is a security platform designed for businesses who want to protect the security of themselves, their clients, and their customers.
whatismyip.cc - External IP Address lookup tool with option to scan the external IP address.
Tenable.io - Tenable.io Cyber Exposure platform helps to protect any asset on any computing platform and eliminate blind spots.
ShowIP - ShowIP displays the IP address(es) of the current page in the status bar.
AlienVault USM (from AT&T Cybersecurity) - AlienVault USM Anywhere delivers powerful threat detection, incident response, and compliance management for cloud, on-premises, and hybrid environments.