Welcome to OpenKJ.org!
Note: If you are going from a version prior to 0.10.0 to 0.10.0 or later, you will need to export your regular singers and playlists BEFORE updating and reimport them after installing the new version and updating your karaoke and break music databases due to database changes.
OpenKJ is open source karaoke hosting software licensed under the GPL version 3. It is currently considered unstable and isn't 100% feature complete, but the primary developer is using it to host shows and it seems to be working fine with the exception of the occasional crash/segfault.
It should build and run fine on any modern Linux distribution as long as the required dependencies are installed (Qt 5.x, gstreamer 1.x). You can follow the source code link to get to the project's GitHub page. This project is developed on Linux and then compiled for the other platforms, so while I make an effort to keep parity between the three platforms and to test changes on all three, the Linux version tends to be the most feature complete and stable.
Binary installers are available for Windows under the downloads link. Please excuse the giant installer size, I need to go through and prune down the gstreamer stuff to the parts actually needed by the program.
There is a *very* experimental installer for Mac OS X in the downloads section. I have no idea if this works outside of the Mac I have for dev/testing. If anyone tests it and runs into problems or even if it works successfully, I'd appreciate it if you'd contact me via Github and let me know.
Travis CI Status