01
Add your WEBM
Drop the file on the panel, choose it from disk, or open it from Your Library. Wait until the name and length appear.
WEBM to MKV
Turn browser WEBM files into Matroska MKV for flexible desktop playback and local archives — right in your browser.
Drop a WEBM file here
or click to choose from your computer
WEBM · VP8 · VP9 · browser recordings
Your file will be converted to MKV. Click Convert when ready.
Converting…
Local processing in your browser · Files are not uploaded to our servers
About WEBM to MKV conversion
WEBM is a web-oriented container. MKV (Matroska) is a flexible open container popular for desktop libraries and backups. Converting WEBM to MKV helps when you want browser captures stored alongside other desktop video in one player-friendly format.
Sound Booster converts in the browser: add a WEBM, encode to MKV, then download or save to Your Library. Everyday files are meant to stay on your device for this step.
Choose WEBM to MKV for local archives, VLC-style playback, and folders where you mix screen recordings with other downloads. For social uploads and many mobile apps, MP4 is still the safer target — use the WEBM to MP4 page when that is the goal.
Large recordings need enough free memory in the tab. If encoding stalls, try a shorter clip first. The progress bar shows approximate percentage while the browser works so you know the job has not frozen.
How to convert WEBM to MKV
02
Convert to MKV
Click Convert to MKV and keep the tab open while the browser encodes. The first run may load a small local encoder.
03
Download or save
Save the MKV file to your device, or store it in Your Library for later tools on Sound Booster.
MOV and MP4 formats
What is a WEBM file?
WEBM is a media container built for the web. Browsers often record or export video as WEBM (for example Chrome screen capture). It typically uses open codecs and plays well in HTML5 players, but many phones, editors, and upload forms still prefer other containers.
What is an MKV file?
MKV (Matroska) is an open container that can hold video, audio, and subtitles. Desktop players such as VLC handle it well. It is a common choice for local libraries when you want flexibility beyond a single commercial upload format.
What people use it for
Desktop media libraries
Store browser WEBM clips as MKV next to other downloads in a single desktop-friendly library.
Playback outside the browser
Open converted files in cross-platform desktop players when you no longer need a web-only container.
Backup of web captures
Normalize a folder of WEBM recordings into MKV for long-term storage on a PC or external drive.
When MP4 is not required
Use MKV for local archives where a website does not force MP4, but you still want something more flexible than WEBM alone.
Frequently asked questions
Should I pick MKV or MP4 from WEBM?
MP4 for phones and uploads; MKV for many desktop library workflows. Choose based on the destination.
Do my files leave this device?
No. Conversion is designed to run in the browser.
Will phones play MKV?
Support varies. For mobile sharing, prefer WEBM to MP4 instead.
Is WEBM to MKV free?
Yes on this page, without a mandatory account.
Why did conversion fail?
Try Chrome or Edge, a shorter file, and keep the tab active until encoding finishes.