Convert images, documents, video and audio in your browser. Your files stay on your device.
Go from AAC to OPUS without installing software: the conversion runs on your device and the files aren’t uploaded anywhere.
Drag one or more AAC files onto the dashed area, or tap it to pick them from your device.
OPUS is already selected: you can adjust bitrate, channels and volume, and trim the track.
Press “Convert to OPUS”. When it’s done, download the files one by one or all together in a ZIP archive.
Good to know. For music, 192 kbps is an excellent compromise; for speech, 64 kbps mono is enough.
Source format
Advanced Audio Coding (ADTS stream)
The successor to MP3, used by YouTube, Apple Music and digital broadcasting. An .aac file contains the “bare” audio stream, with no container.
Target format
Opus Interactive Audio Codec
The most efficient audio codec available today: it’s the one behind WhatsApp voice messages and video calls. At 64 kbps speech is crystal clear and music surprisingly good.
Audio and video use WebCodecs: they work in up-to-date Chrome, Edge, Opera and Samsung Internet, in Firefox 130+ and Safari 17+ (with a few limits on the formats they can create). If your browser can’t create the chosen format, we tell you before you start.
No. The conversion from AAC to OPUS happens entirely in your browser, using your device’s computing power. Files aren’t sent or stored anywhere: when you close the page they’re gone from memory too.
Up to 100 files at a time. There’s no fixed size limit: it depends on your device’s memory. On smartphones it’s best to work in smaller batches with heavy files such as videos.
Yes, with up-to-date Safari, Chrome, Firefox, Edge and Samsung Internet. On phones, converted files end up in the Downloads folder or the Files app.
Only to open the page (and, the first time, to download the components needed for that type of file). After that the conversion keeps working even if the connection drops.