MP4 to MP3
Extract the audio track of a video as MP3.
How to use MP4 to MP3
Add the video — MP4, MOV and WEBM all work.
Click Extract MP3.
The audio track is re-encoded to 192 kbps MP3 in your browser.
Download the MP3 file.
How a video converter can work without uploading your video
Every desktop video tool you have heard of — HandBrake, VLC's converter, most "free online converters" behind the scenes — is a front end to ffmpeg. This page runs the same ffmpeg, compiled to WebAssembly so it executes inside your browser tab. The first conversion downloads that engine (about 30 MB) once; your browser caches it, and every conversion afterwards starts instantly and runs entirely on your own machine.
The trade is honest: you spend one 30 MB download and your own CPU time, and in exchange your video never crosses the network. For a 200 MB clip that is also simply faster — uploading it to a server converter takes longer than converting it locally does.
What you get: the audio track, as a clean MP3
The video stream is dropped and the audio track is re-encoded to a 192 kbps MP3 — the bitrate where music sounds transparent to most listeners and an hour of audio weighs about 80 MB. Lectures, interviews, podcasts recorded as video, and music sets are the classic cases: the picture adds nothing on a commute, and the MP3 plays on every device, car stereo and audio app ever made.
MOV and WEBM work exactly the same way — the container does not matter, only the audio inside it. If the source audio is already MP3 or AAC at a lower bitrate, re-encoding cannot add quality back; 192 kbps is a ceiling chosen so the output is never the bottleneck.
- Lecture and meeting recordings → listenable on the move
- Music performances → straight into a playlist
- Interviews shot as video → audio for editing or transcription
- Voice memos saved as video → small files that attach to anything
Your files stay yours
Every step runs inside your browser, using the WebAssembly and Canvas APIs your device already ships with. No file is uploaded, no copy is kept, and nothing sits in a queue on a server waiting to be deleted — which is also why the tool keeps working with the network disconnected.
For video this is rarer than it sounds: almost every "free MP4 to MP3" site uploads your clip to their server, where it sits in a queue with everyone else's. Running ffmpeg in the browser removes the server from the story entirely — there is nothing to upload to, and nothing for anyone to keep.
The practical ceiling is your device, not a pricing tier: files up to 100 MB are accepted, conversion runs at roughly the speed of your CPU, and there is no daily counter because there is no account and no server keeping one. A meeting recording converts on a laptop in about the time it takes to pour a coffee, and the original video never left the machine it was recorded on.
Frequently Asked Questions
Why does the first conversion take a moment to start?
The video engine (ffmpeg compiled to WebAssembly, ~30 MB) downloads on first use and is cached afterwards. That download is what makes a no-upload video converter possible.
Is there a length limit?
Files up to 100 MB are accepted. Long videos convert at roughly real-time speed, since everything runs on your own device.
Are my files uploaded to a server?
No. The conversion runs entirely in your browser — audio and video never leave your device, which also means no queue and no file-size fees.
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