Opus to MP3 converter that runs in your browser
Voice notes are saved as .opus files, which most players and editors refuse to open. Drop them here and get MP3 or WAV back, in about a second. The conversion happens on your own machine, so nothing is uploaded and there is no file size cap from a server.
Your browser already knows how to decode Opus, so the file is decoded where it sits and re-encoded in the page. Nothing is uploaded, there is no engine to download, and it keeps working with the network switched off.
How to convert an opus file to MP3
This works with a single voice note or with a folder full of them. Batch conversion is the usual case, so it is the default.
- Add your files. Drop in .opus, .ogg, .m4a, .amr, .aac, .wav or .mp3. Select several at once. On a phone, use the file picker to reach your downloads folder.
- Choose the output format. MP3 is the safe default and opens anywhere. WAV is uncompressed and is the better choice if the audio is going into an editor or a transcription tool.
- Convert and download. Conversion starts immediately, with no engine to download first. Take the files one at a time or use Download all.
What you get
Batch conversion
Queue a whole folder of voice notes and download them one by one or all together.
Starts instantly
Your browser decodes Opus natively, so there is no multi-megabyte converter to download before anything happens.
No upload, no queue
Nothing is sent to a server, so there is no waiting behind other people's jobs and no file size limit imposed from outside.
Original filenames kept
Each output keeps the name of its source file, which matters when you are converting dozens at once.
Why voice notes are .opus files
Opus is a modern audio codec built for speech. It sounds better than MP3 at the very low bitrates a voice message uses, which is why messaging apps picked it. A minute of speech can be a few tens of kilobytes.
The trade is compatibility. Opus is younger than MP3 and plenty of software never added support for it, which is why a voice note you saved often refuses to open in a music player, a car stereo, a voice recorder app or an older editing tool.
When to choose MP3 and when to choose WAV
Pick MP3 when you want the file to simply open, anywhere, including on hardware that is a decade old. It is the least surprising format there is.
Pick WAV when the audio is going into an editor or a transcription tool. It is uncompressed, so it is large, but nothing is lost in a second round of compression.
If the file will not play at all
Check the extension first. Files arrive as .opus, .ogg or .oga depending on how they were exported, and some tools mislabel them. This converter accepts all three and works from the contents rather than the name.
Also check the file actually finished downloading. A voice note saved from a chat while the connection dropped can be truncated, which looks identical to a format problem until you try to convert it.
Questions people ask
Is there a file size or file count limit?
No limit is imposed by us, because nothing is uploaded. The practical ceiling is your device's memory. Very long recordings, over an hour, are better converted on a computer than a phone.
Do I have to wait for anything to download?
No. Your browser can already decode Opus, so conversion starts the moment you press the button. A typical voice note finishes in well under a second.
Does this work on an iPhone or an Android phone?
Yes, in a mobile browser. Opus decoding needs a reasonably current browser, so on an older iPhone stuck on an early version of Safari the decode step can fail. The app version has its own decoder and does not depend on the browser at all.
Is the audio uploaded to a server?
No. The conversion runs inside the page on your own device. That is also why there is no queue and no account.
Can I convert to M4A, AAC or back to Opus?
Not here. Browsers will happily decode those formats but do not expose an encoder for them, so this tool writes MP3 and WAV only. The iPhone app can produce the others.
I do not want the audio, I want the words. What then?
Then converting is a detour. Transcribing the voice note directly gives you text you can search, quote and paste, without producing an audio file you then have to listen to.
Keep reading
Not affiliated with, endorsed by, or sponsored by WhatsApp LLC or Meta Platforms, Inc. WhatsApp is a trademark of WhatsApp LLC. This tool is an independent utility that works with files you already have.