MKV to WebM converter
Turn MKV files into WebM for free. The conversion runs entirely in your browser, so your videos are never uploaded anywhere.
How to convert MKV to WebM
- Add your MKV files. Drop one or more .mkv files on the box above, or tap it to pick them from your device.
- Let it convert. The first video you convert loads the converter once (about 31 MB, then cached). After that it runs on your device; a progress bar shows how far along it is.
- Download the WebM. Press Download next to each file. Nothing was sent to a server, so close the tab and it's gone.
What is a MKV file?
MKV (Matroska) is a flexible container that can hold any codec, several audio tracks and subtitles. It is popular for downloads and recordings.
What is WebM?
WebM is an open video format made for the web, usually VP8 or VP9 video with Vorbis or Opus sound. Screen recorders and browsers often save WebM.
Why convert MKV to WebM?
MKV is great for holding many tracks and subtitles in one file, but phones, TVs, browsers and social networks often won't play MKV. WebM is the better choice for web pages and open-source players; keep in mind iPhones, many editors, WhatsApp and some social networks don't accept WebM.
Will I lose quality?
WebM uses lossy compression tuned so the difference is invisible at normal use. We use high-quality settings by default.
Private by design
Most online converters upload your file to their servers. This one doesn't: the converter itself is loaded into your browser and works offline from there, so your videos never leave your phone or computer.
Questions
Is this MKV to WebM converter free?
Yes, completely free, with no sign-up, no watermark and no daily limit.
Are my MKV files uploaded?
No. The conversion happens inside your browser on your own device. Nothing is sent to us or anyone else.
Can I convert MKV to WebM on iPhone or Android?
Yes, in a modern browser. Phones are slower than computers for video, and very long videos can run out of memory on older phones.
Can I convert several files at once?
Yes. Drop as many as you like; they are converted one after another and each gets its own download button.
Is there a file size limit?
No fixed limit, but your browser has to hold the whole file in memory, so files over about 2 GB may fail.