MP4 is the most compatible video format. It plays on phones, TVs, browsers and every editing app. MKV is the Matroska container, popular for films and recordings because it can hold several audio and subtitle tracks. Phones and editors often can’t open it.
Converting to MKV gives you a flexible container for archiving and media servers like Plex and Jellyfin. The conversion happens entirely in your browser, so your files are never uploaded and there’s no size limit beyond your device’s memory.
How to convert MP4 to MKV
- Choose your MP4 file.
- Optionally pick a smaller video size, and set a start and end time if you only need part of it.
- Press Convert and download the MKV.
Questions
Is MP4 to MKV conversion free?
Yes, completely free with no limits, sign-up or watermark.
Are my files uploaded?
No. Conversion runs on your own device, so your files stay private.