Drop videos, or browse
Select several at once to convert them into a ZIP.
avi · flv · mov · mp4 · mpeg · ogg · webm · wmv & more
Click to browse for a video or drag one onto the drop zone.
The options dialog appears with MKV as the destination format; adjust the optional resolution, mute, or compress settings if you want them.
Select Convert and let the browser-based FFmpeg engine take over.
Track the encoding through the percentage shown on top of the video preview.
Your new MKV file lands in your downloads automatically at the end.
MKV, formally called Matroska, is a free, open container prized for its flexibility: it can hold nearly any video or audio codec along with multiple subtitle tracks and chapters. That makes it a favorite for people who archive their media collections or run home streaming setups such as Plex or Jellyfin, where MKV files are first-class citizens.
Convert to MKV when you are standardizing a personal video library on one container, or when a media server in your home network organizes and streams MKV most cleanly. Everything happens in your browser, so even large personal recordings never have to be entrusted to a third-party service.
100% private“No part of your recording travels across the internet. The Matroska file is assembled by FFmpeg running inside your own browser, so the only copy of the video that exists is the one on your device.”
Both are containers, meaning boxes that hold video and audio streams. MP4 is more universally playable on phones and TVs, while MKV is more flexible, supporting virtually any codec plus multiple audio and subtitle tracks, which is why archivists and media-server users prefer it.
Desktop players like VLC handle MKV without issue, and media servers such as Plex and Jellyfin support it natively. Some smart TVs and mobile apps are pickier, so if broad device playback is the goal, MP4 may serve you better.
The video is re-encoded during the conversion, so a small amount of quality loss can occur, as with any transcode. For everyday clips the change is rarely noticeable, and keeping the original file preserves a lossless copy.