Convert webm to mkv
Converted on your device. Files never leave this tab. Output tops out around 2 GB.
Nothing is uploaded
The converter runs inside this page. Cut your network after it loads and it still works.
No account, no daily limit
No sign-up, no daily limit, no watermark, no queue behind other people's files. Batch as many WEBM files as you like.
Real MKV output
Encoded by ffmpeg, the same library the command-line tools use — not a renamed extension.
About WEBM
WebM
An open container from Google, launched in 2010 and based on Matroska, holding VP8, VP9 or AV1 video with Vorbis or Opus audio. Convert from WebM to MP4 for editors, phones and apps that handle MP4 better.
About MKV
Matroska Video
An open container first released in 2002 that can hold almost any video and audio codec, plus several audio tracks, subtitle tracks and chapters in one file. Use it to keep multiple languages and subtitles together; convert to MP4 for devices that do not read MKV.