AnyFormat

00 Opus → MP3

Opus to MP3

For WhatsApp and Discord audio outside those apps.

Drop files or a folder here

or choose from your device · paste with ⌘V / Ctrl+V

.opus

03Options 5

Right for speech, wrong for music. At a fixed quality the file size does not change — but mono tolerates a much lower quality than stereo, so combine the two to actually shrink the file.

Leave at 0 for the whole file.

0 means run to the end.

  • No upload The conversion runs in this tab. Your file never travels — not to us, and not to the advertising.
  • No sign-up, no email, no daily cap There is no account system to sign up to.
  • No size limit we invented Only your device's memory — about ~2 GB on a desktop browser, ~400 MB on a phone.
  • Turn your Wi-Fi off and convert anyway The conversion needs nothing but this page. Ads will not load without a connection; your file will still convert. That is the whole claim, and it takes five seconds to check.

Converts Opus to MP3. Opus is the best general-purpose lossy codec there is, and almost nothing outside a browser or a messaging app will open it — which is the entire reason for this conversion.

Where your .opus came from

WhatsApp voice notes, Signal, Discord, Telegram voice messages, and YouTube's audio streams are all Opus. So are most WebRTC recordings.

It is an excellent codec — better than MP3 at every bitrate, from 6 kbps speech to transparent music — and it has essentially no hardware support. Converting to MP3 trades efficiency for the ability to open the file on a device made before 2015.

Voice notes are already heavily compressed

A messaging voice note is typically encoded at 16–24 kbps mono, tuned for speech over a mobile connection. Converting will not improve it, and using a high MP3 bitrate on it just wastes space encoding what is already missing.

Low quality with mono is the right setting. The result sounds the same and is small.

How MP3 encoding works without a server

Browsers decode MP3 but do not encode it — there is no MP3 encoder in WebCodecs. The encoding here is LAME, the reference open-source MP3 encoder, compiled to WebAssembly and loaded only when you actually convert to MP3.

It is the same encoder desktop software has used for twenty years, producing standard files that play everywhere. Because it is fetched on demand, pages that convert to WAV or M4A never download it.

Other names for this

Also searched as “whatsapp voice note to mp3”, “convert opus to mp3”.

Questions

Where do .opus files come from?
WhatsApp, Signal, Discord and Telegram voice messages, and most WebRTC recordings.
Will converting improve the sound?
No. The source is already heavily compressed for a mobile connection. Use Low quality and mono — anything higher just wastes space.
Is my file uploaded?
No. The demuxing, decoding and encoding all happen in this tab using the browser’s own media stack plus a WebAssembly encoder. A recording can be an interview, a lecture, a private call — none of it is transmitted. Turn your Wi-Fi off after the page loads and it still works.
Can I convert several files at once?
Yes. Drop as many as you like, or a whole folder. Each keeps its original name with the new extension, and you can download them individually or as a ZIP.