OpenAnyFile
Works
Viewing, inspecting and verifying. You get a playback bar with duration and seeking. File details, exact byte size and the detected signature are always shown.
How to open a .au file
The short version: AU is a Sun Audio File from Sun Microsystems. The longer version — including the quirk that trips most people up — is below, along with a viewer that runs entirely on your own device.
What is a .au file?
Sun Audio File is an audio format developed by Sun Microsystems, first appearing in 1992. It is normally produced by Unix systems, early Java applets.
The header is a mere 24 bytes and big-endian. Java's original sound API used it as the default, which is why .au files still turn up inside old applets and system sound folders.
| Full name | Sun Audio File |
|---|---|
| File category | Audio |
| MIME type | audio/basic |
| Magic bytes (file signature) | 2E 73 6E 64 (.snd) |
| Developer | Sun Microsystems |
| Introduced | 1992 |
| Usually created by | Unix systems, early Java applets |
| OpenAnyFile engine | HTML5 audio player |
| Opens without upload | Yes — parsed locally in your browser |
Open a .au file in your browser
OpenAnyFile routes .au to its HTML5 audio player, which plays a playback bar with duration and seeking.
- Open the OpenAnyFile opener in this browser — nothing to download or sign up for.
- Drag your .au file onto the drop zone, click to browse for it, or paste it with Ctrl+V.
- The extension is detected and the file is handed to the HTML5 audio player.
- Your AU opens on its own viewer page: a playback bar with duration and seeking.
- Use fullscreen for a closer look, or download the file back out unchanged. Works the same on Windows, macOS, Linux, Android and iOS, because it is just a web page.
What you can and cannot do with it here
Does not work
Editing and re-saving. OpenAnyFile is a reader, not an editor — for changes you still need special software or an equivalent.
Your {ext} file stays on your device
The entire pipeline — detection, decoding, rendering — runs client-side. Your browser hands the bytes to a decoder compiled to WebAssembly, the result is drawn to the page, and that is the whole journey. No account is created, no file is stored, and no analytics event carries your filename. This is also why there is no size limit imposed by a server: the only ceiling is your own available memory.
Frequently asked questions about AU files
Can I open a .au file without installing special software?
Yes. OpenAnyFile's HTML5 audio player runs in your browser, so you can read a AU file with nothing installed. You get a playback bar with duration and seeking. For full editing you still need the original application — this is a viewer, not an editor.
How can I check a file really is a AU file?
Look at the first bytes rather than the extension. A genuine AU begins with 2E 73 6E 64 (.snd). Opening the file in OpenAnyFile shows that signature in the file-details panel, so a file renamed to .au by mistake is easy to spot.
Is it safe to open a AU file online?
With OpenAnyFile, yes, because nothing is uploaded. The file is read locally through your browser's File API and never leaves your device, so there is no server copy to leak, log or retain. That matters most for the kind of file people are least willing to hand to a random converter site.
What is a .au file, exactly?
Sun Audio File — an audio/basic format created by Sun Microsystems since 1992. The header is a mere 24 bytes and big-endian. Java's original sound API used it as the default, which is why .au files still turn up inside old applets and system sound folders.
Does the same viewer handle formats related to AU?
Yes — the same engine also opens .mp3, .flac, .wav, so you can compare related files without switching tools.
Related formats
These open with the same engine, so if you have one of these sitting next to your .au file, it will open too: