tubesynch has officially been retired and is no longer operating. The source code will remain on github.
Please feel free to fork, modify, and submit pull requests if you'd like to help contribute new features to tubesynch. tubesynch runs on node.js so the primary scripting language is JavaScript. The rest is just basic CSS/HTML/Jade.
tubesynch started out originally as a fork of CyTube (https://github.com/calzoneman/sync/). tubesynch is several versions behind the current cytube master branch so it deserves its own repository as I doubt it's backwards compatible at this point. Feel free to check out CyTube though for a better understanding of the code base.