OGG (Opus) to MP4 Converter
Upload an OGG audio file (Opus codec) to convert it to MP4, entirely in your browser. Straight conversion - no presets, no options -, keeping a similar size to the original, and download an MP4 audio file (AAC) that plays on almost any device or program. Nothing is uploaded to a server, and the audio is gone as soon as you close or refresh this tab.
Current size: · Duration:
The first time, your browser downloads the conversion engine (ffmpeg.wasm, open source) from a content delivery network. Your audio is never uploaded anywhere - it's only processed locally, in your device's memory.
Your converted audio:
Frequently asked questions
Is my audio uploaded to a server?
No. All conversion (decoding the OGG/Opus audio and re-encoding to AAC inside an MP4 container) happens in your browser via WebAssembly (ffmpeg.wasm). The file never leaves your computer, and it isn't saved anywhere - it's gone as soon as you close or refresh this tab. The only thing your browser downloads is the conversion engine itself (an open-source library, not your file), the first time you use the tool.
Why convert from OGG (Opus) to MP4?
Many voice-recording apps, WhatsApp Web and some browser microphones produce OGG files with Opus audio, which doesn't always play well outside Chrome or Firefox (for example on iPhone, some desktop players, or video editors). An MP4 with AAC audio is compatible almost everywhere.
Does the resulting MP4 have video?
No. The generated file is an MP4 that contains only the audio track (equivalent to an M4A, but with an .mp4 extension), ready to play in any audio or video player.
Is there a size or length limit?
A max of 500MB is recommended to keep processing manageable, since everything happens in your device's memory. Very long audio files may take a while and use a fair amount of memory depending on your device.
Why does the conversion take so long?
Conversion runs entirely in your browser, on a single CPU thread, without using any external server. It's slower than a desktop converter or a cloud service, but in exchange your audio never leaves your computer.
Does it work in any browser?
You need a browser with WebAssembly support (every modern browser: Chrome, Firefox, Edge, Safari). On phones, large files may be slow or run out of memory depending on the device.