PNG to WebP

What this tool does, exactly

WebP is what a web page wants: a quarter to a third smaller than a JPEG at the same visible quality, with the transparency a PNG has. This writes one with your browser's own encoder and tells you the saving in bytes, because a conversion that does not measure itself cannot say whether it was worth doing.

What it does

Decodes the picture with your browser's own codec and asks the same browser to encode it as WebP at the quality you chose. Transparency is kept: WebP has an alpha channel, so a PNG logo on nothing stays on nothing.

Where it does not work

Safari's canvas cannot write WebP as of this writing; asked to, it quietly writes a PNG instead. This tool checks the bytes that came back and refuses rather than naming a PNG .webp — the file would be rejected by whatever wanted a WebP, later, with no explanation. Chrome, Edge and Firefox on any system, including a Mac, write it.

The quality choices are named, not numbered

Best for pictures people will look at closely, Balanced for a page, Small for a thumbnail. The size each produced is shown next to the result, which is the feedback a slider never gives.

What is left in the file

Nothing but the pixels. Metadata the source carried is stripped.