Turn your MKV file into a WebM that plays where you need it, right in your browser.
Drag and drop the file, or click to browse. Files up to 500 MB are supported, and nothing is installed.
WebM is already selected, so there is nothing to configure. You can switch formats in the panel if you need to.
We convert on our servers, usually in under a minute. Create a free account to download the WebM, or keep editing the file in REQO.
MKV (Matroska) is an open container that can hold any codec plus unlimited audio tracks, subtitle tracks and chapters. That flexibility makes it great for archives and useless for sharing.
The practical problem: Browsers, phones and social uploads reject MKV almost universally. Editing tools often refuse to import it, or import picture without audio. Nobody can preview it without installing VLC first.
WebM solves that. Streams natively in Chrome, Firefox and Edge with no plugin. VP9 delivers smaller files than H.264 at the same visual quality, which cuts bandwidth on a busy page.
| MKV | WebM | |
|---|---|---|
| Container | Matroska | WebM (Matroska-based) |
| Typical codecs | Almost anything: H.264, HEVC, AV1, VP9 | VP8 / VP9 / AV1 video, Opus audio |
| Best for | Archiving with multiple audio and subtitle tracks | Web embeds and browser recordings |
| Plays on | VLC and desktop players; rarely anywhere else | Chrome, Firefox and Edge; hit and miss elsewhere |
| File size | Depends entirely on the codec inside | Very small at the same quality |
Yes. Convert and preview the result for free, then create a free account to download it. There is no per-file charge and no watermark on the WebM itself beyond the free-plan badge.
No. The conversion runs on our servers and the whole flow happens in your browser, so it works the same on Windows, macOS, Linux, iPhone and Android.
Converting re-encodes the video, so it is not bit-for-bit identical. We encode at a high quality target, which keeps the result visually indistinguishable from the MKV on normal viewing. Converting the same file back and forth repeatedly will eventually show, so keep your original.
Up to 500 MB per file. For anything bigger, trim or compress it first, both are free tools here.
Your upload is processed and then held only as long as your project needs it. Nothing is published, indexed or shared unless you create a share link yourself.
To MP4
Turn your MKV file into an MP4 that plays where you need it, right in your browser.
OpenTo MOV
Turn your MKV file into a MOV that plays where you need it, right in your browser.
OpenTo GIF
Turn your MKV file into a GIF that plays where you need it, right in your browser.
OpenTo WebM
Turn your MP4 file into a WebM that plays where you need it, right in your browser.
OpenTo WebM
Turn your MOV file into a WebM that plays where you need it, right in your browser.
OpenTo WebM
Turn your AVI file into a WebM that plays where you need it, right in your browser.
OpenFree, in your browser, and the file stays open in a full video editor afterwards.