YourListen.com uploads are compatible with 15 different audio extensions. These include: AAC,AC3, AIFF,AMR,CAF,MMF,MP2, MP3, M4A, OGG, RA, WAV, WMA . MP3 uploads are by far the most popular audio extension upload. Are there any other audio extensions you would like to see added to this list? Why are mp3 uploads the most popular of the bunch?? What audio extension format do you feel has the best sound quality?? What do you feel is the next biggest audio extension format on the horizon. We would love to hear your feedback. Chime in here or shoot us an email at support@yourlisten.com