audio converters
Convert MP4 to MP3 online — free & private
Convert MP4 to MP3 with Optimal Convert — free, unlimited and private. Drop the file, download the result: every conversion runs locally in your tab, there’s no account, and it works offline after the first load. Only the audio track is extracted — the video is never re-encoded.
How to convert MP4 to MP3
Add your mp4 file
Drag it into the converter box above, or click to browse. The file never leaves your device.
Output is set to MP3
The dropdown is preconfigured to MP3 (audio track) — switch it any time.
Download your MP3 file
The conversion runs in your tab and the result saves to your device. Nothing is uploaded or stored.
Frequently asked questions
Is MP4 to MP3 really free?
Yes — free and unlimited. No sign-up, no watermarks, no daily caps, no file-size limits. Convert as many files as you like.
Are my files uploaded anywhere?
No. Conversion runs entirely in your browser tab — there is no upload endpoint, so your file’s bytes never leave your device. You can even convert offline after the first load.
Can I convert sensitive or work documents?
Yes. Because nothing is uploaded, private files stay private. That makes Optimal Convert suitable for GDPR- and HIPAA-sensitive workflows without a data-processing agreement.
What MP3 quality do I get?
MP3 output is written by the LAME encoder at up to 192 kbps; the quality slider picks the bitrate. You can also resample (e.g. to 44.1 kHz or 48 kHz) or force mono before encoding to shrink podcast and voice files. WAV output is lossless PCM at the source sample rate.
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Private by design
This page runs entirely in your browser. Files are read, converted and saved on your own device using WebAssembly and the browser’s native codecs — nothing is uploaded, there is no account, and your bytes never leave your machine. Not even we can see them.