Convert MP4 to transparent WebM
Remove a green-screen or solid background from an MP4/MOV clip and export a transparent WebM with alpha for Chromium-based browsers.
The problem
Transparent video on the web is still fragmented. MP4 is broadly supported but does not carry alpha in normal browser playback; GIF supports transparency but only with hard edges.
WebM with alpha is a strong option for Chromium-based browsers, but most simple converters either do not preserve alpha or require command-line FFmpeg.
For short AI-generated green-screen clips, the fastest path is usually to key and encode directly in the browser.
How EasyLottie solves it
EasyLottie decodes MP4/MOV/WebM locally, applies a WebGL chroma key, and records VP8 WebM with alpha when the browser supports it.
The tool disables WebM export on browsers that strip alpha, which prevents false success downloads that look transparent in preview but flatten after export.
If WebM is not a fit, the same keyed result can be exported as Lottie ZIP, transparent GIF, or PNG sequence.
Step-by-step
Use a Chromium browser
Chrome, Edge, Brave, and Arc preserve WebM alpha. Firefox currently strips alpha from MediaRecorder VP8 output.
Drop the MP4 or MOV
Upload a short green-screen or solid-background clip.
Pull the key
Sample the background and tune tolerance, softness, despill, and choke.
Choose WebM
Select transparent WebM output and set size, fps, and quality.
Download and test
Export the WebM and test it over the intended page background.
Real-world use cases
Landing page loops
Use alpha WebM for smooth transparent hero or feature clips in Chromium-heavy audiences.
AI video overlays
Turn a generated subject-on-green clip into an overlay that sits on top of product UI.
Prototype assets
Create transparent motion clips for experiments before committing to a production animation pipeline.
Frequently asked questions
Why not transparent MP4?
Standard browser MP4 playback does not reliably preserve alpha. WebM with VP8 alpha is the practical browser format for Chromium.
Why is WebM disabled in Firefox?
Firefox strips alpha from MediaRecorder VP8 output, so the tool disables that option to avoid broken exports.
Can Safari play transparent WebM?
Safari support is not reliable for this workflow. For Safari-heavy audiences, use PNG sequence or evaluate an alternate delivery path.
Is anything uploaded?
No. Decode, keying, and encoding run locally in the browser.
Can I export Lottie from the same file?
Yes. You can switch output to Lottie ZIP, transparent GIF, or PNG sequence.
Ready to try it?
Free, no signup. 30-second workflow. Your file never leaves your browser.