Open it in a browser first
The fastest way to look at a WebP file is to drag it into a browser tab, or to right-click it and choose your browser as the program to open it with. Every current browser renders WebP natively, on a phone or a computer.
You can also make the browser the default program for WebP files, so a double-click opens the picture straight away. This is a viewing route only: the file stays in WebP format, and the next program you try may still refuse it.
Convert the file when an app refuses it
Older image editors, some Windows photo apps, and plenty of upload forms still expect JPG or PNG. Open the WebP to JPG converter, choose the file, and generate a JPG that those programs accept without complaint.
The conversion happens locally in the browser and the file is not sent anywhere. Inputs are limited to 25 MB, 16,000 pixels per side, and 48 megapixels, which covers images from the web and from a camera alike.
Do not just rename the extension
Changing the letters after the dot from webp to jpg does not convert anything. The bytes inside are still WebP, so careful programs will keep refusing the file, and programs that trust the name may open it and then save a broken copy.
A real conversion rewrites the image data into the new format, which is what those applications actually read. It takes a few seconds and produces a file that behaves correctly everywhere, not just in the app that happened to trust the name.
Static or animated makes a difference
WebP comes in two flavors. A static WebP is a single still picture, while an animated WebP holds a moving sequence like a GIF. The difference decides which programs will accept the file and which tools can work with it.
Filekind accepts static WebP only, and animated files are rejected rather than flattened into their first frame. If you need to work with an animated file, keep it as it is and use a tool built for animation, because a still conversion silently drops the motion.
Choose the output that suits the next step
JPG is the right answer when the file is a photograph or the destination only lists JPG, because it stays small and opens everywhere. Choose PNG when the original has transparency that you need to keep, since JPG has no way to store an empty background.
WebP itself is already small at similar quality, so if your goal is a lighter page rather than compatibility, leaving the file alone is usually the right call. Converting is about what the receiving program accepts, not about which format is better in general.