FSSD to ALAC Converter
Processing entirely on your device — large files may take a moment.
FSSD Audio and Apple Lossless exist for different jobs: FSSD is a raw 8-bit audio dump format from early UNIX sound experiments — tiny headers, bare samples. Convert ALAC to FLAC for non-Apple players, or MP3 for sharing.
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 FSSD compares to ALAC
| FSSD | ALAC | |
|---|---|---|
| Structure | FSSD Audio container | MP4 (alac sample entry) container |
| Compatibility | ffmpeg, archive tools | iOS, macOS, iTunes, ffmpeg |
| Best for | Rescuing legacy audio | Apple-ecosystem lossless libraries |
How to convert FSSD to ALAC
- 1
Select your files
Drag & drop your FSSD 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 ALAC". The conversion runs entirely inside your browser using WebAssembly — no upload, no queue, no waiting.
- 3
Download results
Download each converted ALAC file individually, or grab everything at once as a ZIP archive.
About the FSSD format
FSSD is a raw 8-bit audio dump format from early UNIX sound experiments — tiny headers, bare samples.
ffmpeg decodes it natively inside your browser — the audio track is re-encoded to your chosen format with nothing ever uploaded.
+ Strengths
- ✓Decoded natively by ffmpeg
- ✓Runs entirely in your browser
- ✓Free, private, no watermarks
! Limitations
- −Legacy niche format
- −Modern tools rarely open it
- −Keep the original for archival round-trips
About the ALAC format
ALAC (Apple Lossless Audio Codec) is Apple's FLAC equivalent: bit-exact lossless compression inside an MP4 container, opened-source in 2011 and now native on every Apple device and most server-side pipelines. It is what iTunes Store sells as "lossless" and what iPhone recordings encode to by default.
For non-Apple players FLAC is the safer target, and conversion is sample-exact in both directions — the decode is handled by ffmpeg's native ALAC decoder without any Apple runtime.
+ Strengths
- ✓Native on every Apple device
- ✓Open source since 2011
- ✓Reasonable sizes inside MP4
! Limitations
- −Outside Apple ecosystems FLAC wins
- −Slightly worse ratios than FLAC
- −Confusing .m4a extension doubles as lossy
Why convert FSSD to ALAC?
Converting makes sense where the strengths of ALAC meet what FSSD cannot give you. Native on every Apple device Meanwhile Legacy niche format One pass through the converter above puts your file on the right side of that trade-off.
Frequently asked questions
Is this FSSD to ALAC 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 FSSD to ALAC?
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.
Are tags like title and artist preserved?
Tag handling varies between target formats and this conversion focuses on the audio itself. For archival copies where tags matter, keep the original file; the converted copy is for playback and sharing.
Can I convert a whole folder of FSSD 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.