MKV in the browser
MKV (Matroska) is a flexible open container; WebM is a restricted version of it. Chrome and Edge often play an MKV directly when the video inside is H.264, VP9 or AV1, so it loads instantly. Firefox and Safari usually don't, and then ffmpeg.wasm converts the first 60 seconds locally. Either way, nothing leaves your computer.
OBS recordings to GIF
OBS Studio records to MKV by default because a crash can't corrupt the whole file. For a GIF of a gameplay moment or a software demo:
- Load the MKV and trim to the few seconds you want. If the moment is past the first minute and your browser needs the ffmpeg.wasm route, use OBS's File → Remux Recordings to make an MP4 first; remuxing is instant and lossless.
- Gameplay has lots of motion and colour: keep 256 colours, use 12 to 15 fps and 480 px wide.
- Software demos have flat colour: Dithering: None, 10 fps and 640 px keep text readable and the file small.
Subtitles and multiple tracks
MKVs can hold several audio and subtitle tracks. A GIF has no audio, and subtitles aren't burned in; add your own words with the caption field instead.
The converter first asks your browser to decode the file with its built-in video decoder, the same one that plays videos on web pages. If the browser can't (an unusual container or codec), it loads ffmpeg.wasm, a WebAssembly build of FFmpeg, and converts the first 60 seconds to an editable copy right on your device. That download is about 32 MB, happens once, and still sends nothing of yours anywhere.
Questions
Can I turn an MKV into a GIF without installing anything?
Yes. Open this page, drop the MKV and export. If your browser cannot decode it, the page fetches ffmpeg.wasm and does it locally.
Why is only the first minute available for some MKVs?
When the ffmpeg.wasm fallback is needed, the page converts the first 60 seconds to keep memory use safe in the browser. Remux or trim longer files first.
Are subtitles kept?
No. Use the caption field to add text to the GIF.