Convert MP4 to MP3 online — free, no upload

Need just the audio from a video — a podcast, a lecture, a song? This extracts the audio track as an MP3, entirely on your device.

It uses FFmpeg.wasm, a real build of the FFmpeg encoder compiled to WebAssembly. The engine itself is downloaded once (a few MB); your video file is never uploaded.

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Frequently asked questions

Does this work with video formats other than MP4?

Yes, most common video formats are accepted — the tool detects the input format automatically.

Is my video uploaded to a server?

No. The conversion runs entirely inside your browser. Your video is never sent over the network — see our How It Works page for the technical details.

Is there a video size limit?

We recommend keeping videos under roughly 100–200 MB depending on your device's RAM, since everything is processed by your own browser.

Why does the first conversion take longer?

The first time you use this tool, your browser downloads the FFmpeg engine (about 25 MB). It's cached after that, so later conversions start faster.