WEBM to MKV Converter
Convert WEBM to MKV using your browser's own media codecs — no upload, no watermark, no size limit. Drop a WEBM file below — the whole conversion runs on your device.
Drop files, or click to browse
WEBM files only — processed one at a time
Frequently asked questions
Is this WEBM to MKV converter free?+
Yes, with no watermark and no account. The engine runs locally in your browser, so there's no server queue limiting usage.
Is my video uploaded to a server?+
No. Orbfile uses your browser's own built-in media codecs (via the WebCodecs API and Mediabunny), so encoding happens entirely on your device.
How long will it take?+
It depends on your device and the video's length and resolution — expect roughly real-time to a few times real-time for typical clips.
Is there a maximum file size?+
There's no fixed upload limit — since everything runs on your device, the practical limit is your browser's available memory, which handles typical clips and even fairly long recordings without issue.
How do I convert WEBM to MKV?+
Drop your WEBM file into the box above — Orbfile re-encodes it to MKV using your browser's own codecs and gives you a download link when it's done.
About WEBM and MKV
What is WEBM?
WEBM is an open, royalty-free video format built for the web, typically using the VP9 codec for strong compression at small sizes.
Full WEBM format guide →What is MKV?
MKV (Matroska) is a flexible open container that can hold multiple audio tracks, subtitles, and chapters alongside the video.
Full MKV format guide →The short version: MKV gives you supports multiple audio/subtitle tracks in one file, which helps once you run into WEBM's biggest limitation: less commonly used than MP4 outside web contexts. It's a natural move when your video is headed toward archiving video with multiple language tracks or subtitles.
How it works
- 1
Drop your file in
Drag your video onto the box above, or click it to browse — there's no account to create and no upload to wait on.
- 2
Pick your settings
The output format is already set for this page — just adjust any extra options shown, if there are any.
- 3
Download the result
Your browser processes everything locally and hands you a download link the moment it's done — nothing was ever sent to a server.
Is it private?
Everything happens locally, inside this browser tab. Your video is read from disk, processed with WebAssembly running on your own device, and handed back to you as a download — it's never transmitted anywhere, so there's nothing to intercept and nothing stored on a server.
Common use cases
- Archiving video with multiple language tracks or subtitles
- Uploading a clip to social media
- Sending a video over email or chat
- Freeing up storage on a phone or laptop
Supported formats
This is one of many pairings the video toolkit handles. In total it covers:
Related conversions
Format details
About WEBM files+
WEBM is an open, royalty-free video format built for the web, typically using the VP9 codec for strong compression at small sizes.
Google introduced WebM alongside WebP as a royalty-free alternative built specifically for the browser, most commonly pairing the VP9 (or newer AV1) video codec with Opus audio in a lightweight container. That combination tends to compress noticeably better than the more universally-compatible H.264/MP4 pairing, which is why WebM shows up heavily in web video embeds and platforms like YouTube use it internally, even when they serve MP4 for broader device compatibility.
How to open a WEBM file
Opens readily in Chrome, Firefox, Edge (native), VLC Media Player. For real editing, use DaVinci Resolve, Adobe Premiere Pro (with an extension).
Good for
- excellent compression for web delivery
- royalty-free, no licensing overhead
Watch out for
- less commonly used than MP4 outside web contexts
About MKV files+
MKV (Matroska) is a flexible open container that can hold multiple audio tracks, subtitles, and chapters alongside the video.
Matroska was designed from the ground up as an open, extensible container, meaning a single MKV file can bundle several audio tracks (say, multiple languages), several subtitle tracks, and chapter markers, all switchable during playback — something older containers like AVI and even MP4 handle less gracefully. That flexibility made it the format of choice for archiving TV shows and films with multiple language options, though a handful of phones and streaming devices still expect MP4 and need MKV converted first.
How to open a MKV file
Opens readily in VLC Media Player. For real editing, use DaVinci Resolve, Adobe Premiere Pro (with an extension).
Good for
- supports multiple audio/subtitle tracks in one file
- open format, no licensing fees
Watch out for
- not natively supported by some phones and TVs without an app
Need a different format? Try the full Video Converter, or explore all video tools.