Exporting a transparent WebP
Begin with real transparency
The source needs an alpha channel if you want transparent output. An opaque white rectangle will remain opaque after conversion.
Inspect small edges
Thin lettering and semi-transparent contours can reveal compression artifacts. Check the exported file on both a light and a dark background.
Watch browser output
If a browser does not implement a requested canvas export type, it may return PNG instead. RSWebPForge checks the output type and stops rather than giving the file an incorrect extension.
Try the workflow
Try a photograph at quality 80, then compare fine details. The best setting depends on the image, and some sources will already be efficiently encoded.
Open webp converter