Turn WebM videos into MKV. It is converted in your browser, so the file never leaves your device.
Drop WebM files here
or choose from your computer paste with Ctrl V
from Photos or Files
Ready · other file types work too0 bytes uploaded, ever
Drop WebM files onto the box above, or click it to choose them. ToAny reads the file's contents to detect the type, so a wrong extension does not matter.
Press Convert. Open Options first if you want to change the defaults. The work happens in this tab and can take a while for large files.
Save the MKV, or download everything as one ZIP if you converted several files.
The WebM to MKV converter is part of this page and runs inside your browser. Your videos are never sent to ToAny or to anyone else.
Nothing has to travel to a server and back, so work starts the moment you press Convert. How long it takes depends on your device and the size of the file.
No sign-up, no email address and no watermark. Add several files and download them together as a ZIP.
WebM does not play on many phones, TVs or in most video editors. MKV can carry several audio and subtitle tracks in one file. WebM is at home in royalty-free video on websites; MKV is the usual choice for films with several audio and subtitle tracks.
The defaults suit most files. Under Options you can lower the resolution, trade quality against file size, remove the sound and trim the start and end. This is demanding work for a browser: a long or high-resolution file can take several minutes, and your device does all of it, so keep the tab open.
The conversion uses your browser's own video and audio codecs (WebCodecs), with hardware acceleration where the device has it; the file is read from disk as it goes and can be up to 2 GB. Where the browser lacks a codec, the page falls back to the compatibility engine. A video over 500 MB cannot be kept at full quality in browser memory; choosing a lower resolution or quality under Options lets it fit.
WebM is an open, royalty-free video format built for the web. It is a restricted form of Matroska holding VP8, VP9 or AV1 video. Browsers play it; iPhones, TVs and video editors often do not.
Opens in Chrome, Firefox, Edge and recent Safari; few TVs and editors
WebM converterMKV is an open container that can hold practically any video and audio format plus multiple subtitle tracks. That flexibility is why it is popular for films, and why Apple devices and browsers refuse it.
Opens in VLC, Plex and many TVs; not iPhones, QuickTime or most browsers
MKV converter| WEBMWebM video | MKVMatroska video | |
|---|---|---|
| Stands for | WebM | Matroska |
| Type | Video container | Video container |
| Compression | Lossy | Depends on what is inside |
| Usually contains | VP8, VP9 or AV1 video with Vorbis or Opus audio | Almost anything: H.264, HEVC, AV1, several audio and subtitle tracks |
| Introduced | 2010, by Google | 2002, by the Matroska project |
| Opens in | Chrome, Firefox, Edge and recent Safari; few TVs and editors | VLC, Plex and many TVs; not iPhones, QuickTime or most browsers |
| Best for | Royalty-free video on websites | Films with several audio and subtitle tracks |
| File extension | .webm | .mkv |
No. The WebM to MKV conversion runs inside your browser, on your own phone or computer. The file is not sent to ToAny or to anyone else.
It depends on what is inside the WebM. When its video and audio are already in a form MKV can hold, they can be carried over without being compressed again. Otherwise they are re-encoded, which costs a little quality. Under Options you can favour quality or a smaller file.
Yes. Add as many as you like, convert them together and download each result or all of them as one ZIP.
The steps are the same everywhere because ToAny runs in the web browser: open this page in a current version of Chrome, Edge, Safari or Firefox, add the WebM file, press Convert and save the MKV. There is nothing to install.
Yes. Files up to 2 GB are accepted, and a video over 500 MB needs a lower resolution or quality chosen under Options so the result fits in memory. Beyond that the limit is your device's memory, since nothing is uploaded; a computer copes with large files better than a phone.