The best free option is (for Windows).
How to View & Edit WebP Files in ACDSee: The Essential Plugin Guide acdsee webp plugin
Struggling to open WebP images in ACDSee? You are not alone. Here is how to find, install, and configure the right WebP plugin for ACDSee to handle next-gen image formats. If you have downloaded a WebP image from the web recently, you have probably tried to open it in ACDSee only to see an error message or a blank thumbnail. The best free option is (for Windows)
The ACDSee WebP plugin turns a frustrating "unknown format" into a seamless part of your photo workflow. Install it once, and you will forget WebP was ever an issue. Here is how to find, install, and configure
Author’s Note: Always download plugins from the official ACDSee site or trusted sources like CopyTrans. Avoid random DLL download sites.