Bulk CAF to M4B Converter Online — Free HD Quality
Drag and drop your multiple CAF files into this free online CAF to M4B converter (.caf to .m4b), and click the Convert button to bulk convert them to M4B format in HD quality. Use the quality slider to fine-tune your M4B output, then download your converted files one by one or as a single ZIP — your original CAF files are removed from our servers right after.
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PNG, JPG, WebP, GIF, HEIC, RAW, PSD, SVG and more
Max 100MB per file
CAF vs M4B — File Format Comparison
| Feature | CAF | M4B |
|---|---|---|
| File Extension | .caf | .m4b |
| MIME Type | audio/x-caf | audio/mp4 |
| Compression Type | Lossless | Lossy |
| Metadata Support | Yes | Yes |
What Is CAF Format?
Core Audio Format — Apple's flexible container for macOS and iOS supporting any codec (AAC, ALAC, PCM, MP3) with no file-size limit, used internally by Xcode, Logic Pro, and macOS system sounds.
- Compression: Lossless
- Tags & Metadata: Supported
What Is M4B Format?
MPEG-4 Audiobook — AAC audio in an MP4 container with bookmarking support, the standard format for audiobooks on Apple Books, Audible exports, and iPhone podcasts.
- Compression: Lossy
- Tags & Metadata: Supported
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