Select the MP4 file you want to convert
Click convert and watch the progress - the file never leaves your device
Preview the result and download your MKV file instantly!
Converting MP4 files to MKV has never been this easy, free, and secure!
Fublix's MP4 to MKV converter is 100% free and has no limits! Use it as many times as you want without paying anything.
No files are uploaded or sent to any server. The entire conversion takes place locally in your browser. 100% safe and secure.
No limit on the number of files you can convert. Convert as many files as you need, whenever you need.
MP4 is the most universally supported video format, but sometimes you need a different container - WebM for the open web, MOV for Apple workflows, or MKV for archiving.
MKV is the archivist's container of choice - open, flexible, and able to hold virtually any codec, subtitle, and audio track.
Our converter reads the MP4 file and produces a clean MKV file you can use anywhere. The conversion uses your device's built-in hardware-accelerated media engine, so it's fast and nothing is ever uploaded.
Most online converters upload your MP4 file to a server for processing. Fublix doesn't - the conversion runs entirely inside your browser, and your file never leaves your device.
Free, unlimited, no watermark, and no registration required.
