Hey there! I'm iffyloop, the developer of StemRoller. I built this app as a small utility tool for my friend, but later realized others might also benefit from a convenient and intuitive tool for instrument/vocal separation, so I cleaned it up and released it as an open-source project. If StemRoller has helped you in some way and you're feeling extra generous, then any amount you're able to give would be super appreciated!