Short answers for the converter on webp-jpg.com. The tool itself is on the home page.
FAQ
Will JPEG look worse than WebP?
JPEG is lossy. At quality 85–92 photos look close. Graphics with type or UI edges are better as PNG.
What happens to transparency?
JPEG has no alpha. Transparent pixels are painted onto the background you pick (white or black).
Are files uploaded?
No. Decode and encode run in the tab.
Can I convert a whole folder?
Drop up to 20 WebP files. Download one by one or as a ZIP when two or more are done.
Animated WebP?
You get a still JPEG of the drawn frame. For a moving file, convert to GIF on webptools.com or mp4togif.net.