AU to FLAC Converter
Processing entirely on your device — large files may take a moment.
AU is the µ-law audio format of old Unix systems and Java applets — tiny mono files from another era. Convert to FLAC when you want a permanent, lossless archive of your music.
iLoveConverter processes everything locally on your computer, which makes it private and fast: no upload wait, no server storage, no limits. Add as many files as you like — batch conversion is built in.
How AU compares to FLAC
| AU | FLAC | |
|---|---|---|
| Compression | µ-law or PCM | Lossless (~50–60% of PCM) |
| Quality | Mono voice-grade (µ-law) | Bit-perfect |
| Compatibility | Legacy Unix tools | Players, Android, hi-res rigs |
| Best for | Old system sounds and recordings | Music collections and archival |
How to convert AU to FLAC
- 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 FLAC". The conversion runs entirely inside your browser using WebAssembly — no upload, no queue, no waiting.
- 3
Download results
Download each converted FLAC 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 FLAC format
FLAC (Free Lossless Audio Codec, Xiph, 2001) compresses audio to roughly 50–60% of its PCM size and restores every bit on playback — a ZIP for music that also carries proper tags, hi-res support up to 32-bit/655 kHz on paper (24-bit/192 kHz in practice) and full open-source pedigree. It is the archive format of digital music collections.
Support followed maturity: every serious player, modern Android (system-level), most cars and streaming purists' devices handle FLAC natively. Apple resisted for years but iOS 11+ plays it, with the caveat that iTunes/Apple Music syncing still prefers ALAC. The price of losslessness is size — about five times MP3 at comparable quality.
+ Strengths
- ✓Bit-perfect lossless with real compression
- ✓Hi-res capable (24-bit/192 kHz)
- ✓Open, unpatented, tag-native
! Limitations
- −~5× the size of lossy formats
- −Apple syncing prefers ALAC
- −Overkill for casual listening
Why convert AU to FLAC?
Think of it as moving your file to the container that fits the job. µ-law flavor sounds dated and mono FLAC works differently: Bit-perfect lossless with real compression If any of that sounds like your task, run the conversion — it takes seconds and nothing leaves your device.
Frequently asked questions
Is this AU to FLAC 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 FLAC?
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.
Will converting AU to FLAC reduce audio quality?
If FLAC is lossless, the output contains everything the AU file contains — no further loss is added. If FLAC 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.
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.