MKV to WEBM Converter
Convert MKV to WEBM online for free. Fast, secure, and high-quality conversion with no sign-up or software required.
Maximum file size is 1GB
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Three steps to your converted file
Everything happens in your browser tab - upload, pick a format, download. The heavy lifting runs on our servers.
Upload your file
Drag and drop, click to browse, or paste a URL. Batches take up to 20 files at once - 230+ input formats across video, audio, image, document, and archive types.
Choose an output format
Pick from over a hundred output formats. Filter by category or search by name - every option is open to everyone, no account needed.
Convert & download
Hit Convert and grab your download link moments later. Originals are erased when the job completes; results are cleared within about an hour.
What is an MKV file?
The Matroska Video (MKV) file is an open-standard, free container format capable of holding an unlimited number of video, audio, picture, or subtitle tracks in one file. Unlike proprietary containers, Matroska is structured upon Extensible Binary Meta Language (EBML), allowing for significant flexibility and forward compatibility. It supports a vast array of codecs, including H.264, VP9, HEVC, AAC, Vorbis, and FLAC, and is particularly noted for its support of soft subtitles (SSA/ASS) and chapter entries, making it a standard for high-definition video distribution (HD) and anime fansubs.
How to open an MKV file
Native support for MKV is available in Windows 10/11 via the Movies & TV app and generally on Linux distributions. macOS requires third-party software, as QuickTime Player does not natively parse the Matroska container. The industry-standard solution for all operating systems is VLC Media Player, which includes built-in libraries for decoding the diverse codecs often encapsulated within MKV files. Alternative options include MPV and MPC-HC (Windows).
MKV Technical Info
- Full Name
- Matroska Video Container
- Developed By
- Matroska (non-profit)
- Initial Release
- 2002
- MIME Type
- video/x-matroska
What is a WebM file?
WebM is an open, royalty-free audiovisual media file format sponsored by Google, derived from the Matroska (MKV) container. Designed specifically for the HTML5 video element, it restricts streams to specific codecs: video is compressed using VP8, VP9, or AV1, while audio utilizes Vorbis or Opus. The format structure is defined by a subset of the Matroska specifications, prioritizing efficiency for web streaming and low computational overhead for decoding in browser environments.
How to open a WebM file
As a native HTML5 format, WebM files open directly in modern web browsers including Google Chrome, Mozilla Firefox, Microsoft Edge, and Opera without plugins. For offline playback, cross-platform media players like VLC media player, MPV, and FFmpeg-based tools provide full support. Windows Media Player may require the installation of WebM Media Foundation Components to render these files.
WebM Technical Info
- Full Name
- Web Media
- Developed By
- Initial Release
- 2010
- MIME Type
- video/webm
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Why RunConvert
The fastest way to convert any file
Purpose-built for speed, privacy, and breadth of format support.
Convert MKV to WEBM in seconds
Every MKV to WEBM conversion runs on our servers, so your device stays fast and the output quality stays intact.
Fast, cloud-powered
No queue, no waiting. Files are processed on high-performance servers and returned in seconds, even for large files.
Secure & private
Encrypted in transit and never shared with anyone. Uploads are erased the moment your job completes, and results shortly after.
Free - no account needed
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Developer API
Convert MKV to WEBM via API
Automate MKV to WEBM conversions in three steps: create a job, upload your file, then poll for the result.
# 1. Create job
curl -X POST https://api.runconvert.com/v3/jobs \
-H "Authorization: Bearer YOUR_API_KEY" \
-H "Content-Type: application/json" \
-d '{
"tag": "mkv-to-webm",
"tasks": {
"upload-file": {
"operation": "import/upload"
},
"convert": {
"operation": "convert",
"input": "upload-file",
"output_format": "webm"
},
"export-result": {
"operation": "export/url",
"input": "convert"
}
}
}'
# 2. Upload your file (use upload_url from the response)
curl -X PUT "$UPLOAD_URL" --upload-file input.mkv
# 3. Poll for result
curl https://api.runconvert.com/v3/jobs/$JOB_ID?include=tasks \
-H "Authorization: Bearer YOUR_API_KEY"Replace YOUR_API_KEY with your RunConvert API key. Get your free API key at runconvert.com/api.