IPvFoo adds an icon to the toolbar, showing a large red 4 or green 6 to indicate whether the outer page was fetched using IPv4 or IPv6. If the page connects to other domains, a smaller 4 or 6 appears alongside. When you click the icon, a table appears with a row for each hostname. See the icon tooltips for more information. Clicking on a hostname or address will select it for convenient copying. There is also a right-click option to look up addresses on bgp.he.net. IPvFoo is Free Software (Apache 2.0 license). I made this to raise everyday awareness of the global IPv4 to IPv6 transition. To respect your privacy, it keeps data in RAM and treats the network as read-only. I can maintain this without ads because there are no server costs.