What is AU?
Sun Microsystems developed an audio file format that later went on to be used in computers developed by NeXt called Sun Microsystems Audio. These audio files use the AU file extension and are a lossless audio file format that is associated with the µ-law encoding method. The format had toll-quality sound meaning that the quality of the sound would be as good as the voice quality of sound transmitted over a phone line. At that time, this was considered good quality but the format has been improved since then so that the sound quality is much better. The format structure has been expanded on as well to include a header that has information about the data rate, channels, and data length.
AU files are still supported on Linux systems and on some media players but the format is not popular. Often times, a user is more likely to find a service or app that can convert an AU file to a more common format than to find an app that can play the AU file.
How do I open an AU file online?
As mentioned, the AU format is old and while you may find desktop apps that can play this format, finding an online player is much more difficult. If you want to share an AU file and make sure it can be played without your recipient having to jump through hoops to set up a player or convert it, you can upload it to Jumpshare which supports playback for this format.
Alternatively, if you can’t find an app that plays AU files, you can upload the one you want to play to Jumpshare and listen to it. Jumpshare will play the file in your browser; you can pause the file, adjust volume, and jump to any position in the clip.