About converting video
This tool converts a video between formats — MP4, WebM, MKV and MOV. It re-encodes the video in your browser using ffmpeg compiled to WebAssembly, so your file is never uploaded. There is no watermark and no sign-up.
How Video Converter works
How to use it
- Drop or choose a video.
- Pick the output format.
- Convert and download.
How it works
The tool decodes your video and re-encodes it into the format you choose — H.264 for MP4 and MOV, VP9 for WebM — using ffmpeg in WebAssembly. Because re-encoding is computational, conversion happens at a slower-than-native speed and longer clips take more time.
Private and free
The engine downloads once (~32 MB) and is cached; nothing is uploaded. For best speed, use shorter or smaller files.
Common uses
- Convert MOV to MP4
- Convert MKV to MP4
- Make a WebM for the web
- Change a video format
- Convert for compatibility
- Prepare a video for upload
- Convert a phone recording
- Re-encode a clip
Frequently asked questions
How do I convert a video?
Drop it, choose the output format, then convert and download.
Is my video uploaded?
No — conversion runs in your browser with ffmpeg WebAssembly.
Why is it slow?
In-browser re-encoding is slower than native; shorter, smaller files are quickest.
Which formats are supported?
Convert to MP4, WebM, MKV or MOV from most common inputs.
Why is the first run slow?
The engine (~32 MB) downloads once, then is cached.
Is there a watermark?
No — the output is clean.
Is there a file-size limit?
Large files may exceed browser memory; try smaller clips.
Is it free?
Yes — completely free with no sign-up.