Saved an image and it won't open? Make it a JPG.
Websites send WebP because it's small, but plenty of apps still can't read it. Add a batch, or use the six test files built in your browser. Each file is opened and checked by its first bytes, not its name, for animation, transparency and metadata, so nothing is quietly lost. Everything is converted here, on your device.
Apps read the first bytes of a file, not its name. A WebP starts with RIFF, a size, then WEBP. A JPG starts with FF D8 FF. Rename one and some apps refuse it while others quietly open it as WebP, which is why "it works on my laptop" so often fails at the print shop. Sites often save WebP under a .jpg name too, like the test file named download (1).jpg. Pick any file from the batch to see its real first bytes before and after.
The same photo was encoded by your browser as JPG and as WebP at six qualities, and every file decoded and scored. Matching on equal score (PSNR), not on the quality number, shows what WebP saves a site and what you pay back by converting. Converting also adds a second round of loss on top of the WebP's, which is why quality 85 or more is the default here.
The top rows are tested live in the browser you're using now. The rest are the first versions that opened WebP without plug-ins. If the app you're sending to is older, or isn't listed (many print shops, CMS uploads and email clients), send JPG.