Bragi

Convert your MP3 audiobooks into M4B format with chapters, metadata, and cover art — all in one step.

Bragi takes a folder of MP3 files and produces a single, bookmarkable M4B audiobook file with proper chapter markers, so you can pick up right where you left off in Apple Books or any audiobook player.

Features:
- Drag and drop a folder of MP3s to get started
- Automatic chapter markers from individual files
- Preserves or lets you edit title, author, genre, and cover art
- Smart preset selection based on your source audio quality
- Mono downmix for spoken audio (saves ~50% file size)
- Detects fake stereo sources automatically
- Built-in queue for converting multiple books
- Add finished audiobooks directly to Apple Books
- Native macOS app — fast, private, no internet required

All conversion happens locally on your Mac. No files are uploaded anywhere.