About MKV and AIFF

MKV is the Matroska container — a flexible box that can hold nearly any codec. OBS and most screen recorders write it by default.

AIFF is Apple's uncompressed audio format — the same raw PCM as WAV in a different wrapper, dating back to 1988. It's still the native interchange format for Logic Pro and much of the mac production world, and converts to WAV with zero quality change.

Extracting audio from MKV re-encodes only the audio track — the video is discarded, so even long files finish quickly.

How the conversion works

This tool runs FFmpeg — the same engine behind most media software — compiled to WebAssembly, entirely in your browser. Your file is read locally, converted locally, and saved straight from memory; nothing is ever uploaded, which also means no queues and no server-side file size limits.

The converter itself is a one-time ~31 MB download on your first conversion, cached by the browser afterwards. Once it's loaded, everything works offline.