AU Audio — A .au file is a AU Audio. It is an audio format used to store music, voice and sound effects, either lossy or lossless.
Quick facts
What is .au
A .au file is a AU Audio. It is an audio format used to store music, voice and sound effects, either lossy or lossless.
In the mime-db registry it maps to audio/basic, and it is marked as non-compressible. When serving .au over HTTP, set the Content-Type header as shown in Developer info below.
Related entities: it maps to audio/basic — and is delivered over HTTP via the Content-Type header.
How to open .au files
Developer info
When served over HTTP, responses should set the following header:
Content-Type: audio/basic
Common software that reads/writes .au:
Relation chain
Related extensions
Related MIME types
Common uses
How to edit .au files
How to create .au files
Frequently asked questions
Common options include VLC, Windows Media Player, Audacity. You can also open many of these files with built-in viewers or a browser.
Create a new file in any text editor or the app that owns the format and save it with the .au extension.
audio/basic is the media type identifier used for .au files during network transfer (for example in the HTTP Content-Type header).
Sources & standards
Updated 2026-08-18
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