Convert MKV to MP4
MKV is a flexible container but few web players or mobile devices support it. Drop your MKV below and vexo re-encodes the video as MP4 (H.264 + AAC) — entirely in your browser.
Drop your video here
or choose a file from your device
Max 200 MB per file. Conversion runs in your browser.
Every conversion runs entirely in your browser. Your video never leaves your device.
About MKV → MP4
Why convert MKV to MP4?
MKV (Matroska) is great for archiving but poor for sharing — most browsers, iOS devices, smart TVs and editors can't open it directly. MP4 plays everywhere.
What about subtitles or multiple audio tracks?
vexo keeps the primary video and audio track in the converted MP4. Multiple audio tracks and embedded subtitles are not preserved in this version — if you need them, use a desktop tool.
Is anything uploaded?
Nothing. vexo loads ffmpeg-wasm into your browser and runs the transcode locally.
What you're converting between
A short primer on both formats so the trade-offs are obvious before you hit Convert.
MKV
SourceMatroska · introduced 2002
MKV (Matroska) is the most flexible video container in common use — it can wrap virtually any video codec, any audio codec, multiple subtitle tracks and chapter metadata in a single file. That makes it the default choice for archives, encodes from physical media, and downloads that need to ship subtitles. The catch: very few browsers, iOS devices, smart TVs or editors open MKV directly. Converting to MP4 gives you the same video stream in a container the rest of the world actually plays.
Strengths
- Holds anything — video, audio, subtitles, chapters
- Open, royalty-free container
Trade-offs
- iOS, most browsers and TVs cannot play it directly
- vexo keeps only the primary video and audio track when converting
- Subtitles and secondary audio are not preserved
MP4
TargetMPEG-4 Part 14 · introduced 2001
MP4 is the default video container of the modern web. With H.264 video and AAC audio it is the format every iPhone, Android phone, Windows machine, Mac, smart TV, video editor, social platform and browser understands without extra codecs. vexo encodes MP4 with the H.264 'veryfast' preset and 128 kbps stereo AAC — a safe default for talking-head, music and screen recordings.
Strengths
- Plays on every device and player on Earth
- Hardware-decoded on phones and laptops
- Compact at quality 70–80 for most content
Trade-offs
- Slightly larger than WebM at the same perceived quality
- H.264 has licensing concerns for some use cases (not for end-users)
Popular conversions
Each link below opens the converter pre-tuned for that conversion.
Supported formats
MP4 is the safest default for web and mobile playback. WebM gives the smallest files for modern browsers. GIF is for short, soundless animations.
WMV, FLV and other legacy/streaming formats are not supported in this version. Please convert those to MP4 first using a desktop tool.
| Format | Input | Output | Notes |
|---|---|---|---|
| MP4 | Yes | Yes | H.264 + AAC, broadest compatibility |
| MOV | Yes | No | Apple/QuickTime container; convert to MP4 |
| WebM | Yes | Yes | VP9 + Opus, smaller than MP4 |
| MKV | Yes | No | Container; convert to MP4 or WebM |
| AVI | Yes | No | Legacy container; convert to MP4 |
| GIF | Yes | Yes | No audio, short clips only |
| WMV | No | No | Not supported |
| FLV | No | No | Not supported |
Frequently asked questions
Your videos never leave your device
vexo is a static page. Every conversion runs inside your browser via ffmpeg compiled to WebAssembly. There is no server-side processing, no upload, no temporary file, no cache. When you close this tab, every file is gone.
- No account required.
- No server processing. Your videos stay on your device.
- No caching, no Service Worker, no IndexedDB persistence.
- The conversion engine (ffmpeg-wasm) is fetched from a public CDN and cached by the browser; no personal data is sent.