Built for audiobook listeners,
by audiobook listeners.
M4BConvert is a free, browser-based tool for converting and creating M4B audiobooks. No account, no upload, no limit, and every conversion runs entirely on your device.
What it is
M4BConvert gives you four focused tools for working with M4B audiobook files directly in the browser:
- M4B → MP3 > split an audiobook into one MP3 file per chapter.
- M4B → M4A > extract chapters as M4A files in a lossless copy.
- MP3 → M4B > merge multiple MP3 files into a single chaptered M4B.
- M4A → M4B > do the same with M4A source files.
Every tool includes a chapter editor, a live log, and a progress indicator that stays responsive even during long jobs.
Why we built it
Most online converters ask you to upload your file to a server, wait in a queue, then download a result (adding latency, file size caps, and a privacy trade-off you never agreed to). For audiobooks, which can be several gigabytes and often contain purchased content, that model felt wrong.
M4BConvert is the tool we wanted when we needed to split an audiobook for a device that wouldn't play it, or merge a set of chapter MP3s from a library download into a single file. None of the tools we found did all of that, locally, and for free. So we built it.
Who it's for
Anyone who listens to audiobooks and occasionally needs to move or reformat them: listeners juggling multiple apps and devices, people working with library downloads, anyone ripping their own CD audiobooks, and anyone who wants a quick one-off conversion without installing software or handing a file to a third party.
Our principles
Local-first, always
No server ever receives your audio. Processing happens on your own hardware, under your control, regardless of file size.
No friction
No account, no subscription, no watermark, no file size cap enforced by us. Drop a file, configure, convert, download.
Transparent by default
The documentation explains the full technical pipeline so you can decide for yourself whether to trust it.
Actively maintained
We track upstream changes and browser API updates. When something breaks, we fix it.