M4B to ALAC Converter
Processing entirely on your device — large files may take a moment.
Convert ALAC to FLAC for non-Apple players, or MP3 for sharing. If your files are still in M4B format, this page is the shortcut: M4B is the audiobook flavour of M4A — AAC audio with chapter markers, used by Audible and Apple Books.
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 M4B compares to ALAC
| M4B | ALAC | |
|---|---|---|
| Compatibility | Apple Books, Audible | iOS, macOS, iTunes, ffmpeg |
| Best for | Chaptered audiobooks | Apple-ecosystem lossless libraries |
How to convert M4B to ALAC
- 1
Select your files
Drag & drop your M4B 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 M4B format
M4B is M4A wearing an audiobook badge: the same AAC audio in an MP4 container, plus chapter markers that Apple Books and Audible apps render as a scrubbing timeline. Buy an audiobook outside Audible and it likely arrives as M4B.
The format is deliberately chained to Apple's book ecosystem. Converting M4B to MP3 sets the book free: car stereos, gym players, old iPods and every app without chapter support will play it — though the chapter marks themselves are flattened away.
+ Strengths
- ✓Chapter markers survive on Apple platforms
- ✓Efficient AAC audio
! Limitations
- −Chapters vanish in MP3 conversion
- −Non-Apple support is patchy
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 M4B to ALAC?
There is a concrete reason this conversion exists: Chapters vanish in MP3 conversion ALAC sidesteps that — Native on every Apple device If that is your situation, the tool above settles it in seconds, entirely on your device.
Frequently asked questions
Is this M4B 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 M4B 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.
Will converting M4B to ALAC reduce audio quality?
If ALAC is lossless, the output contains everything the M4B file contains — no further loss is added. If ALAC 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 M4B 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.