Video Converter
Convert MP4 WebM MOV MKV AVI
Convert MP4 WebM MOV MKV AVI Runs locally in your browser
About the
The Video Converter moves videos between MP4, WebM, MOV, MKV and AVI without uploading anything. Re-encoding runs locally through ffmpeg compiled to WebAssembly, so the same codecs that power desktop conversion software are doing the work inside your browser tab.
Conversions pick the right codec per container: H.264 for MP4 and MOV for maximum device compatibility, VP9 and Opus for WebM for the web, and stream copy for MKV and AVI where the video stream can pass through untouched and finish in seconds.
Use it when a camera produces MOV your editor will not take, when a platform wants WebM, or when you need an MKV that plays everywhere.
Where people use the
- Turning camera-produced MOV into universally playable MP4.
- Preparing WebM versions of a video for a website.
- Wrapping files into MKV to carry extra audio tracks.
- Fixing files an editor or platform refuses to import.
How to use the
- 1
Add your video
Drop in any common video file. The source format does not matter; ffmpeg reads almost everything.
- 2
Choose the target
Pick MP4, WebM, MOV, MKV or AVI. H.264 targets re-encode; MKV and AVI copy the video stream when possible.
- 3
Convert
Click convert and watch the progress. WebM (VP9) is the slowest mode; everything else is quick.
- 4
Download
The converted file is offered for download immediately, with the original size shown for comparison.
Tips and best practices
- If MP4 output will not play somewhere, try WebM as a fallback for web players.
- Converting the same file twice degrades quality; convert from the original each time.
Frequently asked questions
Which format should I choose?
MP4 for sharing and phones, WebM for websites, MOV if something in the Apple ecosystem demands it, MKV to keep multiple audio tracks and subtitles, AVI only for legacy tools.
Does converting lose quality?
Re-encoding does, slightly. MKV and AVI use stream copy where possible, which is mathematically lossless. For MP4/WebM the default settings are visually transparent.
Can it convert 4K video?
Technically yes, but browser memory is the limit. 1080p is comfortable on desktop; 4K may fail on phones or low-memory machines.
Is my video uploaded anywhere?
No. The entire pipeline runs in your browser. The only network traffic is the ffmpeg engine download on first use.