Play any .mkv,
in any web app.
A WebAssembly Matroska engine that remuxes to fragmented MP4 on the fly — dozens of codecs, ASS/SSA subtitles via libass, offline audio transcoding. Drop the headless engine into an existing player, or embed our ready-made video.js player. No re-encoding on a server. Nothing uploaded.
A whole media stack, shipped as WASM.
The container is parsed in Rust, remuxed to fMP4, and fed to a <video> element through Media Source Extensions — codecs the browser can already decode just play.
In-browser remux
MKV → fragmented MP4 on the fly. No transcoding on the common path, no second copy, nothing leaves the machine.
Switch tracks live
Multiple audio tracks with switching mid-playback — flip languages or commentary without a reload.
Real subtitles
ASS/SSA rendered with libass through JASSUB — styled, positioned, karaoke and all. Not a flattened bitmap. Render two subtitle tracks at once whenever you want them.
Offline transcoding
Audio the browser can't decode (Vorbis, DTS core…) is transcoded to AAC/Opus in the browser with a bundled ffmpeg.wasm — served from your own origin.
Instant seeking
Seeks via the Matroska Cues index with a warmed cold-start — byte-ranges straight from the origin, no full download.
Framework-agnostic
A small wasm-bindgen JS API. Wire it to video.js, your own controls, or a fully headless pipeline — no framework lock-in.
Building something commercial with it?
The code is AGPL-3.0 — great for open source, but its copyleft may not fit closed products or hosted services. I'm not selling commercial licenses just yet, but if you'd want one, tell me what you're building and I'll get the process going.
WASM remux engine
The Rust→WebAssembly Matroska → fMP4 remuxer as a headless module. Drop it into an existing player, product, or system — feed it a URL, get MSE-ready fMP4 back, no server transcoding. A small wasm-bindgen JS API you can wire to any UI.
The video.js player
Our complete video.js-based player — the remuxer, libass subtitles and ffmpeg.wasm audio already wired together. Embed a full, production-ready MKV player in your own web app under a commercial license (planned) instead of the AGPL.
Hosted player
Don't want to run anything? Point our hosted embed at your existing MKV/WebM files and they just play — metered, white-label, nothing to deploy. A separate product with its own page.
Interested in future commercial licensing? Tell me about your use case and I'll keep you updated.