Change Video Format
Convert MP4, MKV, MOV, AVI and WebM right in your browser
100% private. Your file is processed locally in your browser with WebAssembly — it is never uploaded to a server, stored, or seen by anyone.
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Change Video Format converts your video between the most common container formats — MP4, MKV, MOV, AVI and WebM — so a file plays on the device, editor or platform you need. Pick a target format, and the tool either remuxes the existing audio and video streams into the new container (fast, zero quality loss) or re-encodes them when the codecs aren't compatible with that format.
Everything runs locally in your browser using ffmpeg compiled to WebAssembly (ffmpeg.wasm). Your video is never uploaded to a server — it stays on your device from start to finish, which makes the tool a private, no-signup option for anyone converting confidential footage, client work, or personal recordings on a slow or metered connection.
Why use this tool
Lossless when possible
When source and target codecs match, the tool remuxes instead of re-encoding, so you get the new container in seconds with zero quality loss and almost no change in file size.
Five containers, one tool
Convert freely between MP4, MKV, MOV, AVI and WebM without juggling multiple apps or installing desktop software like a full ffmpeg or video converter.
Completely private
Your footage is processed entirely in your browser via WebAssembly and never uploaded, making it safe for confidential client work, internal recordings, and personal videos.
No installs or signup
Everything runs in the browser tab — no software to download, no account to create, and no watermark added to your converted video.
How to use the Change Video Format
Add your video
Drag and drop your video onto the page or click to browse and select a file in MP4, MKV, MOV, AVI, WebM or another common format.
Choose the target format
Select the output container you need — MP4 for broad compatibility, MKV for multi-track flexibility, MOV for Apple workflows, AVI for legacy tools, or WebM for the web.
Let it remux or re-encode
The tool automatically copies the streams into the new container when codecs are compatible for a lossless result, or re-encodes them when the chosen format requires it.
Wait for in-browser processing
Watch the progress as ffmpeg.wasm converts the file locally on your device — nothing is uploaded, so the speed depends on your CPU and the file size.
Download the converted file
Save the new video in your chosen format directly to your device, ready to play, edit, or upload.
Popular use cases
- Converting an MKV or AVI download to MP4 so it finally plays on your phone, smart TV, or in a web browser.
- Repackaging a MOV recording from an iPhone into MP4 to upload it to a platform or editor that rejects MOV.
- Switching a video to WebM to embed it on a website with smaller file sizes and modern browser support.
- Standardizing a folder of mixed-format clips into one container before importing them into a video editor.