Why do I get an error when I choose WebP output on my iPhone or in Safari?

Showing and saving are different things

A browser that opens and displays a WebP image is not necessarily able to create a new one. Compression in the Image compressor is done by the browser itself: the tool draws the image onto a Canvas and asks the browser to encode it in the chosen format. If the browser has no WebP encoder, the web standard lets it return PNG instead, and that is what happens.

Why an error instead of a file?

• If the tool accepted that output, you would get a PNG far larger than you expect, possibly larger than the original.
• If it were named .webp, some platforms or programs would reject it because its content does not match its extension, and you would waste time hunting for the reason.
• So the tool checks the type of every output file and shows, next to the file, the message 'Your browser cannot save images as WEBP', suggesting another format or a newer browser.

What to do now

1. The quickest fix: switch the output format to JPEG on the same device, and the tool works straight away. JPEG is accepted almost everywhere.
2. If you really need WebP, open the tool on a computer in a current version of Chrome, Edge or Firefox, which normally can save WebP.
3. Update your browser and system, since format support changes with updates.
4. On an iPhone, browsers generally run on the same engine as Safari, so switching apps there may not help.

Do I even need WebP?

Not always. In our tests on photographic product images, JPEG sometimes came out close to WebP at the same quality, while WebP clearly won on other images and on transparent ones. If your photos are ordinary pictures with no transparency, JPEG output on your current device may be all you need. If you need transparency and a small file together, that is worth moving to a computer for. And if you already have WebP files you want in another format, use the Image format converter.