Video to MP3 pulls the sound out of a video and gives you an MP3 file. Typical reasons: you want to listen to a lecture or a webinar on your commute, you need the audio of a clip to edit in another app, you recorded a concert or a speech with your phone camera, or you want a voice track to transcribe later.
The conversion runs in your browser. The first time, it downloads a converter of about 32 MB and keeps it; after that, the video is processed on your own phone or computer and never uploaded. That makes it quick, because there is nothing to send, and private, because the file stays with you. It also works the same whether the video is 10 MB or 400 MB, as long as your device has enough memory.
It converts MP4 to MP3, and MOV from an iPhone, WebM, MKV and other common formats too. Files can be up to 500 MB. The limit you are more likely to hit is the memory of your device: a phone or an older laptop may struggle with a long, high-resolution video, while a desktop handles it easily. If that happens, close other tabs or try on a computer. In our tests a 2-minute video converted in 3 seconds and a 12-minute one in 7 seconds.
If the video has no sound track, for example a screen recording made without audio, you'll get a message saying so instead of a silent file.
One thing it doesn't do: download videos from YouTube or other sites. It converts files you already have, which keeps you on the right side of the platforms' rules.
Once you have the MP3, you can keep going in the same window. Send it to audio to text to get a transcript with timestamps, or get subtitles for the original video. The MP3 is also saved in your library, in this browser.
In-browser conversion runs on ffmpeg.wasm (GPL). Source code: https://github.com/ffmpegwasm/ffmpeg.wasm