MKV to WebM Offline Converter
Convert MKV videos to WebM format completely offline in your browser
Loading Processing Engine
This tool uses FFmpeg.wasm. The first run downloads the engine (~25MB) — cached after.
Drop your MKV files here
or click to select
Output Files
Why Use This Tool
Web Native
WebM is natively supported by all modern browsers without plugins.
Smaller Files
VP9 codec produces 30-50% smaller files than H.264 at the same quality.
100% Private
No upload required. Conversion happens entirely in your browser.
Frequently Asked Questions
Why convert MKV to WebM?
WebM is the open web standard for video. It is supported by Chrome, Firefox, Edge, and Safari natively, while MKV needs a player like VLC.
Are my files uploaded anywhere?
No. Processing is entirely client-side via FFmpeg.wasm — files never leave your browser.
How big can my files be?
Limited by your device's RAM. ~2GB on desktop, smaller on mobile. Browser memory is the constraint.