The PianoTrax app allows you to play your PianoTrax mp3s directly from your mobile device. You can stream them from your account using WiFi or a cellular connection. You can also download them onto your phone so that you can access the trax in "airplane" mode. You can connect your device to a bluetooth speaker to use for auditions. You can browse Select Songs and Shows and search the PianoTrax Store to add additional songs to your library.