While the official version of XChat for Windows is shareware, it is legal for anyone to compile XChat on their own for personal use, or for others. There are not many of these unofficial builds that are active. In all cases, normally it will be a while before a build is updated to the latest release after a new XChat release. For 2.8.6, these builds appeared to be running as YChat.
There are several other builds available, however they have not been updated to 2.8.6. For a comparison of the different XChat builds, see the Build Lineup