IPvFooBar is a browser add-on for Chrome that provides a convenient way to display the server IP address and a realtime summary of IPv4, IPv6, DNS, WHOIS, and HTTPS information. It is a fork of the original IPvFoo add-on by pmarks.net, with new features and improvements.

When you visit a webpage, you will see an icon in the location bar indicating whether the page was fetched using IPv4 or IPv6. If the page contains elements from other domains, smaller numbers will appear alongside for those domains. Clicking on the icon opens a table with detailed information for each domain.

The table includes a padlock icon to indicate the protocol used (HTTP, HTTPS, or a mix of both), the IPv4 or IPv6 address, and a symbol to indicate if the address is cached. Additionally, starting from Chrome 58+, the table also shows an "S" for WebSocket handshakes.

IPvFooBar also includes new features such as WHOIS, reverse DNS, ARIN and RIPE hyperlinks, and various fixes. It uses the Google DNS API for reverse DNS queries.

IPvFooBar is a free add-on and is available under the Apache 2.0 license.