Webconverger is ‘opensource’ software using Debian packages, where the Debian social contract applies. Even the build process is free software. It does unfortunately include the non-free software Adobe Flash in the package list.
There is a 100% Free software version of Webconverger in the noflash section in http://download.webconverger.com/noflash/
Apple MacOSX has some Free software under the hood and a Free rendering engine Webkit. Well done Apple, though everything open source would be far better.