Convert Opus to MP3
Voice notes from chat apps, turned into MP3s you can play, share or transcribe, without leaving your device.
- Nothing is uploaded
- Works offline after first use
- Open source
- No sign-up, no watermark. The limit is your device’s memory (phones hold less).
Convert .opus voice notes from WhatsApp, Telegram and Signal to MP3 in your browser. It is free, needs no account and adds no watermark, and your files are not uploaded: everything runs in your browser on your device. The limit is your device’s memory, which is smaller on a phone, and after your first run the page works offline.
Your iPhone may take a few seconds to prepare the video first, longer if it's stored in iCloud.
Done
Open the network tab. Your files never appear in it.
Add files and run the tool to see every request this tab makes.
Your files are processed on this device and never sent to a server. Reload the page to clear everything from memory.
Opus is the codec behind almost every voice note sent today. WhatsApp exports voice messages as .opus files, Telegram and Signal use it too, and Discord and many web meeting tools record with it. It is excellent at squeezing speech into tiny files, but Windows Media Player, many car systems, older iPhones, most transcription upload forms and some court and HR systems will not open a .opus file.
Voice notes are personal by nature. Uploading one to a free converter hands a stranger’s server a recording of you or someone you know. Here the Opus audio is decoded by your browser and encoded as MP3 in the same tab; after your first run you can switch to airplane mode and convert.
This page opens at 96 kbps mono, which is more than a voice note needs: a five-minute message comes out under 4 MB. Raise the bitrate and switch to stereo only for music.
How it works
- Export the voice note from the chat app, then drop the .opus file here or tap to pick it.
- Keep 96 kbps mono for speech. Choose stereo and a higher bitrate for music.
- Convert, and the MP3 downloads.
In your browser, not on a server
Your browser decodes the sound track with the same audio decoders it uses to play media on any website (AAC for MP4, MOV and M4A; Opus or Vorbis for WebM; FLAC, WAV and MP3). The samples are resampled to 44.1 kHz and handed to LAME, the reference MP3 encoder, compiled to WebAssembly and served by this site. WAV files are written directly by a few lines of code in the page. Everything happens in memory in your tab.
Compared with upload-based tools: Online converters upload the whole video just to keep its sound, cap free files at a few hundred megabytes, and make you wait in a queue. Home videos, lectures and voice memos are personal. Here the file never leaves your device, so a 1 GB video converts as fast as your computer can read it, and the limit is your device’s memory (phones hold less).
Verify it yourself. Give the page a short while after your first run to save itself for offline use, then turn off Wi-Fi or switch to airplane mode and run the tool again. Or open your browser's developer tools (F12, or Cmd-Option-I on a Mac), pick the Network tab, and watch it while you convert. The panel above does the same count for you.
Questions
How do I get a WhatsApp voice note as a file?
On a phone, long-press the voice message, tap Share or Forward, and save it to Files or send it to yourself by email. In WhatsApp Desktop or Web, hover the message and choose Download. You get a .opus or .ogg file; both work here.
Why is the MP3 bigger than the Opus file?
Opus is much more efficient than MP3 at low bitrates, especially for speech. An MP3 needs roughly twice the bitrate for similar clarity, so the file grows.
Can I convert a whole chat export at once?
Yes. Drop every .opus file from the export folder; each becomes an MP3 and they download together as a zip.
Is the file uploaded anywhere?
No. There is no server in this process. The page is a static file and the work is done by code running inside your browser tab. Give the page a short while after your first run to save itself for offline use; then you can turn off Wi-Fi and it still works.
More video and audio tools
Video to MP3
Pull the sound out of a video, or turn any audio file into an MP3. Your files are converted on this device and never uploaded.
Trim audio
Cut a song, a voice memo or a podcast down to the part you want, with fades if you like. Done on this device, never uploaded.
Audio converter
Turn any sound file into MP3, WAV, FLAC, M4A or OGG. Your files are converted on this device and never uploaded.
Screen recorder
Capture your screen, one window or a tab, with its sound and your voice. The video is made in this tab and never uploaded.
Other conversions
Guides
- How to convert a video to MP3This is different from muting a video: you want the sound saved as its own file. Most devices have no built-in way to do that.
- Is Convertio safe?Convertio is a well-known converter with a published deletion policy. For private files, the safer choice is a converter that never receives them.
- Is Zamzar safe?Zamzar is one of the oldest online converters. Its storage window is longer than most, which is the detail worth knowing.
- A free CloudConvert alternative for everyday filesCloudConvert measures its free tier in credits tied to conversion time, not files, which makes it hard to predict when you will hit the limit. Here is an alternative with nothing to meter.
- A free Convertio alternative with no file size capConvertio's free plan caps both file size and how many conversions you get per day. Here is an alternative with no such ceiling.