AU to CAF Converter
Processing entirely on your device — large files may take a moment.
Convert CAF files to WAV or MP3 for use outside the Apple ecosystem. If your files are still in AU format, this page is the shortcut: AU is the µ-law audio format of old Unix systems and Java applets — tiny mono files from another era.
This converter runs entirely in your browser using WebAssembly — your files never leave your device, nothing is uploaded, and there are no watermarks, sign-ups or queues. Drop in several files at once to convert them as a batch.
How AU compares to CAF
| AU | CAF | |
|---|---|---|
| Compatibility | Legacy Unix tools | afconvert, Logic Pro, ffmpeg |
| Best for | Old system sounds and recordings | Apple pro-audio workflows |
How to convert AU to CAF
- 1
Select your files
Drag & drop your AU files onto the area above, or click to browse. You can add multiple files at once for batch conversion.
- 2
Convert instantly
Click "Convert to CAF". The conversion runs entirely inside your browser using WebAssembly — no upload, no queue, no waiting.
- 3
Download results
Download each converted CAF file individually, or grab everything at once as a ZIP archive.
About the AU format
AU is Sun Microsystems' audio format from the Unix workstation age: a small header followed by µ-law (or PCM) samples. Java's applet era shipped it everywhere, and old Unix sound tooling still emits it.
Modern players increasingly skip it. Converting AU to WAV preserves the samples bit-for-bit while moving the file into universal territory — the standard rescue path for system sounds and old recordings.
+ Strengths
- ✓Simple, lossless sample storage
- ✓Native to old Unix/Java tooling
! Limitations
- −µ-law flavor sounds dated and mono
- −Dropped by modern players
About the CAF format
CAF (Core Audio Format) is Apple's container for pro audio: 64-bit file offsets for recordings of any length, any codec as payload (PCM, ALAC, AAC), and time-stamped MIDI-style event chunks. Logic Pro exports it and macOS system sounds ship in it.
ffmpeg decodes the common PCM/ALAC payload variants, converting CAF to WAV or MP3 for use in any non-Apple DAW, player or web player.
+ Strengths
- ✓64-bit offsets — no size ceilings
- ✓Native to Logic Pro pipelines
- ✓Flexible codec payload
! Limitations
- −Apple-centric — rare outside macOS
- −Some CAF variants (UUID chunks) unsupported
- −Tag metadata Apple-specific
Why convert AU to CAF?
There is a concrete reason this conversion exists: µ-law flavor sounds dated and mono CAF sidesteps that — 64-bit offsets — no size ceilings If that is your situation, the tool above settles it in seconds, entirely on your device.
Frequently asked questions
Is this AU to CAF converter really free?
Yes — completely free, with no sign-up, no watermark and no daily conversion limits. The site is supported by advertising.
Are my files uploaded to a server?
No. The conversion runs entirely inside your browser using WebAssembly, so your files never leave your device — that is what makes it instant and private.
Does it work on Windows, Mac, iPhone and Android?
Yes. Anything with a modern browser works: Windows, macOS, Linux, Android and iOS. No software installation is required.
Is there a file size limit for AU to CAF?
The only limit is your device's memory, since nothing is uploaded. Files up to a few hundred megabytes work fine on a modern desktop browser; very large files simply take a little longer.
Can I convert a whole folder of AU files?
You can select many files at once and they are processed in a single batch. Output files land in one ZIP download when there is more than one result.
Will converting AU to CAF reduce audio quality?
If CAF is lossless, the output contains everything the AU file contains — no further loss is added. If CAF is lossy, one recompression pass is unavoidable; the quality slider controls how much. Loss that already happened in the source file can never be undone by converting.