WEBM to MKV Converter

Repack WEBM videos into versatile MKV containers online

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Settings

The codec to encode the video track. Codec "Without reencoding" copies the video stream from the input file into output without re-encoding if possible.
Set output AVC (H.264) encoding profile. The older the target device, the "lower" profile you should set. More info can be found on the wiki.
Set output AVC (H.264) profile level. Leaving this setting in "Auto" will calculate the correct level and is the best choice in most cases. More info can be found on the wiki.

webm

WebM is an open, royalty-free multimedia container format developed by Google and launched at the Google I/O conference in May 2010. The format pairs the Matroska container (a subset of MKV) with VP8 or VP9 video codecs and Vorbis or Opus audio codecs, creating a fully open media stack designed specifically for web use. Google released WebM alongside the VP8 codec under permissive BSD-style licensing, removing patent and royalty barriers that hindered the adoption of H.264 for open web video. The WebM container inherits the efficient binary structure of Matroska while restricting it to web-optimized profiles, ensuring fast parsing and lightweight implementation in browsers. WebM with VP9 achieves compression efficiency competitive with H.264 High Profile and approaching HEVC, making it practical for delivering high-quality video at reduced bandwidth. Major web browsers including Chrome, Firefox, Edge, and Opera support WebM playback natively, and YouTube uses VP9 in WebM as a primary delivery format for much of its content. The format supports features such as alpha channel transparency in video, making it valuable for compositing web graphics and overlays. More recently, WebM has been extended to support AV1 video, continuing its evolution as a vehicle for open codec adoption. The combination of competitive compression, zero licensing costs, and universal browser support makes WebM a cornerstone of royalty-free web multimedia delivery.
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mkv

MKV (Matroska Video) is an open-standard multimedia container format developed by the Matroska project, which announced the format in December 2002. Named after the Russian matryoshka nesting dolls, the format is built on the Extensible Binary Meta Language (EBML), a simplified binary variant of XML that provides a flexible and forward-compatible structure. MKV can hold virtually unlimited numbers of video, audio, and subtitle tracks within a single file, supporting codecs from H.264 and HEVC to VP9 and AV1 for video, and AAC, FLAC, Opus, and DTS for audio. A standout feature is comprehensive subtitle support, handling formats from simple SRT text to complex ASS styled subtitles and bitmap-based PGS tracks from Blu-ray discs. MKV also supports chapter markers, attachments (such as fonts needed for styled subtitles), and tagging metadata, making it one of the most feature-rich containers available. The open specification) ensures that any developer can implement MKV reading and writing without licensing fees, which has driven widespread adoption across media players, streaming tools, and encoding software. The ability to encapsulate virtually any codec combination in a single, well-organized file has made MKV the preferred container for high-quality video distribution, archival, and personal media libraries.
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Superior Container

MKV holds multiple audio and subtitle tracks plus chapter markers — upgrading your WEBM video with rich, structured metadata capabilities.

Flexible Encoding Options

Choose your preferred video codec, resolution, and bitrate before converting WEBM to MKV — full control over the output file.

Private File Handling

Uploaded WEBM files are deleted right after processing and MKV results are purged within 24 hours. Your content remains secure.

How to convert WEBM to MKV

1

Select or drag&drop WEBM video to convert it to the MKV format from your computer, iPhone or Android. Moreover, it is possible to choose it from your Google Drive or Dropbox account.

2

Now your video is uploaded and you can start the WEBM to MKV conversion. If it is needed, change the output format to one of the 37 video formats supported. After that, you can add more videos for batch conversion.

3

If you want, you can customize such settings as resolution, quality, aspect ratio and others by clicking the gear icon. Apply them to all the video files if necessary and click the button "Convert" to process.

4

Once your video is converted and edited, you can download it to your Mac, PC or another device. If necessary, save the file to your Dropbox or Google Drive account.

About formats

WebM is an open, royalty-free multimedia container format developed by Google and launched at the Google I/O conference in May 2010. The format pairs the Matroska container (a subset of MKV) with VP8 or VP9 video codecs and Vorbis or Opus audio codecs, creating a fully open media stack designed specifically for web use. Google released WebM alongside the VP8 codec under permissive BSD-style licensing, removing patent and royalty barriers that hindered the adoption of H.264 for open web video. The WebM container inherits the efficient binary structure of Matroska while restricting it to web-optimized profiles, ensuring fast parsing and lightweight implementation in browsers. WebM with VP9 achieves compression efficiency competitive with H.264 High Profile and approaching HEVC, making it practical for delivering high-quality video at reduced bandwidth. Major web browsers including Chrome, Firefox, Edge, and Opera support WebM playback natively, and YouTube uses VP9 in WebM as a primary delivery format for much of its content. The format supports features such as alpha channel transparency in video, making it valuable for compositing web graphics and overlays. More recently, WebM has been extended to support AV1 video, continuing its evolution as a vehicle for open codec adoption. The combination of competitive compression, zero licensing costs, and universal browser support makes WebM a cornerstone of royalty-free web multimedia delivery.
Developer: Google
Initial release: May 19, 2010
MKV (Matroska Video) is an open-standard multimedia container format developed by the Matroska project, which announced the format in December 2002. Named after the Russian matryoshka nesting dolls, the format is built on the Extensible Binary Meta Language (EBML), a simplified binary variant of XML that provides a flexible and forward-compatible structure. MKV can hold virtually unlimited numbers of video, audio, and subtitle tracks within a single file, supporting codecs from H.264 and HEVC to VP9 and AV1 for video, and AAC, FLAC, Opus, and DTS for audio. A standout feature is comprehensive subtitle support, handling formats from simple SRT text to complex ASS styled subtitles and bitmap-based PGS tracks from Blu-ray discs. MKV also supports chapter markers, attachments (such as fonts needed for styled subtitles), and tagging metadata, making it one of the most feature-rich containers available. The open specification) ensures that any developer can implement MKV reading and writing without licensing fees, which has driven widespread adoption across media players, streaming tools, and encoding software. The ability to encapsulate virtually any codec combination in a single, well-organized file has made MKV the preferred container for high-quality video distribution, archival, and personal media libraries.
Developer: Matroska
Initial release: December 6, 2002

Frequently Asked Questions

Why convert WEBM to MKV?

MKV supports multiple audio tracks, subtitle streams, and chapters in a single file — features WEBM lacks, making MKV ideal for media collections.

What plays MKV files?

VLC, MPC-HC, Kodi, Plex, and most smart TVs handle MKV natively. It is the most popular container for high-quality home media libraries.

Does MKV support high resolutions?

MKV handles everything from standard definition to 4K HDR content. It imposes no resolution limits and supports all modern video codecs.

Will multiple audio tracks be preserved?

MKV can hold several audio tracks — converting from WEBM lets you later add additional language tracks or commentary to the container.

Is batch conversion available?

Upload multiple WEBM videos at once and convert the entire batch to MKV — efficient for organizing large video collections.

WEBM to MKV Quality Rating

4.7 (734 votes)
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