Audio
Turn your MP3 files into Opus in seconds. Everything happens in your browser: nothing is uploaded to any server.
Drag your files here
Or paste them with Ctrl+V. They never leave your device.
It loses some quality with each re-encode and, at the same size, sounds worse than AAC or Opus. As Opus it takes minimal space with very good quality, ideal for voice and the web.
MP3 compresses sound lossily, removing what the ear barely notices, so a song takes just a few megabytes.
Strengths: Any phone, car, speaker, player or program plays it, however old.
Limits: It loses some quality with each re-encode and, at the same size, sounds worse than AAC or Opus.
Opus is a modern, open codec that gives very good quality at a very small size, for both voice and music.
Strengths: It is the format of WhatsApp voice notes and video calls, and sounds good even at 96 kbps.
Limits: Some old, car or Apple players do not recognise it.
No. The MP3 to Opus conversion runs entirely in your browser, with code downloaded from this site and executed on your device. You can check it in the Network tab of the developer tools or by going offline after the page loads.
A little, because Opus is lossy; at 192 kbps or more the difference is hard to hear.
Up to 2 GB on desktop and 500 MB on mobile (less on low-memory devices), and up to 12 hours of audio on desktop. If it is over, you are told before it starts.
Yes. Drop as many MP3 files as you like: several are converted at the same time, depending on your processor cores, and when they finish you can download each Opus or all of them in a ZIP.