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About M4AtoMP3.org

M4AtoMP3.org is a free set of audio conversion tools built around one simple idea: converting a file should never require handing it to a stranger. Every converter on this site runs inside your own web browser, so your recordings, music and videos stay on your device from start to finish.

Why we built it

Converting an iPhone voice memo or a song from M4A to MP3 is one of the most common audio tasks there is. Yet most online converters upload your file to a server, make you wait in a queue, cap the file size, and sometimes add watermarks or ask for an email address. That felt backwards when modern browsers are powerful enough to do the work themselves. So we built a converter that does exactly that — and made it free, with no accounts and no limits.

How it works

When you add a file, your browser decodes it using its built-in audio decoders (the same ones it uses to play web video). The decoded audio is then encoded to MP3 by LAME, the well-known open-source MP3 encoder, compiled for the web and running in a background worker. For formats the browser can’t decode — and for encoding AAC (M4A) files — we use ffmpeg compiled to WebAssembly. All of this executes locally on your CPU. No audio data is transmitted to us or anyone else.

Our principles

  • Privacy first. No uploads, no server-side processing, no storage of your files.
  • Genuinely free. Every feature is available to everyone. The site is supported by clearly labelled advertising, never by selling data.
  • Honest guidance. We explain trade-offs plainly — including when converting won’t help, such as turning an MP3 into a lossless file.
  • Fast and accessible. Lightweight pages that work on phones, tablets and computers, with keyboard navigation and screen-reader labels.

Our content

Our blog and converter guides are written by the team that builds the converters. We test the advice against real files and update articles when software or devices change. If you spot a mistake, please let us know.

Open-source credits

This site stands on the shoulders of excellent open-source projects: FFmpeg and ffmpeg.wasm, the LAME MP3 encoder and its JavaScript port, fflate for ZIP creation, and Astro for the website itself.

Start converting

Try the M4A to MP3 converter, or jump to WAV, MP4, FLAC, AAC or OGG to MP3.