What is MKV?
MKV (Matroska) is a flexible open container that can hold several audio tracks, subtitles and chapters in one file. It’s popular for recordings and video archives, for example from OBS. But many devices – iPhones, some smart TVs, consoles – and editing programs don’t accept MKV. MP4 is the most compatible video format there is.
What may change
MP4 is less flexible than MKV. The main video and audio are converted; extra audio tracks, some subtitle formats and chapters may not be carried over. Picture quality stays very close to the original. Converting large or long MKV files takes time, because your device does the encoding itself.
How to convert
Drop your MKV above, MP4 is already selected, click “Convert” and download. FFmpeg runs inside your browser, so nothing is uploaded and there’s no server queue.