MKV or MP4?
- Keep MKV for a Plex, Jellyfin, Emby or Kodi library — players there handle it natively.
- Choose MP4 for phones, messengers, editing apps and TVs from a USB stick — see MKV to MP4, which changes the format in seconds without re-encoding.
What is kept
- Video and audio, re-encoded smaller.
- Subtitle tracks inside the MKV are not carried over by the browser encoder — for files with subtitles use the TV & USB section, which repacks MKV without touching the tracks.
For big libraries
Add a whole folder: subfolders are kept, and you can keep adding files while others are being compressed.
Questions
Does it keep embedded subtitles?
No — subtitle tracks are dropped when the video is re-encoded in the browser. Use the TV & USB tools to repack files with subtitles without re-encoding.
How much smaller will MKV files get?
Usually 2–4× for camera and screen recordings; rips that are already compressed shrink less.
Is there a size limit?
No. Files of any size work, because nothing is uploaded.
Last updated: 2026-10-30