Requires RB3Enhanced with HTTP enabled for it to work (check your rb3.ini). You also need a PC hosting this app server on your local network.
You can download the app here (clone the repo locally):
https://github.com/samuelgagnon/RB3SongPicker
P.S.: Regarding code quality, it's a disaster. If anyone wants to take the ideas and make a complete re-write/refactoring/fork (thinking about the team behind RB3Enhanced), well, have fun 😅! I don't plan to maintain this project so much other than my personnal needs and my parties friends feedbacks. That being said, I already used it twice for parties and it works for my needs, so it might also work for you too!