For a customer in the music industry, a desktop application was developed that allows the user to manage concert pieces and export them as playlists, so that the selected pieces can later be played on real instruments (e.g., church or concert organs). The pieces are stored as MIDI files in an encrypted database. In order to give the user a realistic preview of the original sound, a software synthesizer was implemented, which allows a natural sounding playback based on samples of the original instrument. The application was written in C++ using the Qt framework. The graphic user interface was implemented in QML.