Free online WebM→MKV converter. Fast, private, no sign-up.
Going from WebM to MKV takes a couple of clicks: drop the file in, download the result. Drop in your WebM file (a .webm) and download a ready-to-use MKV file (a .mkv) — no software to install, no account to create, and no watermark on the output.
WebM is an open, royalty-free video format built for the web, usually VP9 or AV1 — smaller than MP4 at similar quality and well supported in browsers.
MKV (Matroska) is a flexible open container that can hold almost any codec plus multiple audio tracks and subtitles, popular for archiving.
Most people convert WebM to MKV for compatibility — a website, app or device insists on MKV, and WebM simply won't open. MKV is widely supported, which makes it a dependable target. The conversion runs through ffmpeg, the industry-standard media engine, re-encoding the streams with sensible high-quality defaults so the result plays cleanly on your target device.
Typical uses: preparing assets for a website, attaching a file someone else can definitely open, or standardising a folder of mixed files into one format.
Privacy is the default here. Your WebM file is uploaded over an encrypted connection, converted, downloaded the moment it's ready, and then deleted automatically a short time afterwards. We never keep your files, never build a library of your content, and never make you sign up to download the result.
Ready? Use the converter above, or explore related conversions: turn WebM into a different format, or convert another format into MKV. Everything on Convert Me Pls is free, unlimited and watermark-free.
Yes. Convert Me Pls is completely free with no sign-up, no file-count limits and no watermarks added to your output.
Your files are uploaded over an encrypted connection, converted, and then deleted automatically a short time afterwards. We never keep your files and never build a library of your content.
We use the best available encoders (libvips, ImageMagick and ffmpeg) at high-quality settings for the cleanest possible result.
Conversions run on our servers and support large files comfortably; very large media is processed in a streaming pipeline.