WebP is already an efficient modern format, but exported WebP files are often encoded conservatively and still have room to shrink. We measured it on three images: a WebP saved at quality 90 gave up another 36 to 47 percent here, with an average pixel difference of about 1.5 out of 255 brightness levels. Saved at quality 80 it gave up 19 to 35 percent, and a lossless WebP gave up 60 to 94 percent.
Compresso re-encodes each file at the sweet spot between size and fidelity, then verifies the result pixel by pixel, so the image you download looks exactly like the one you uploaded.
This is ideal for web performance: smaller WebP means faster Core Web Vitals and less bandwidth, with no visible quality cost. If a smaller version can't be produced without crossing the visual line, the original is returned unchanged — you never lose.
Drop up to 20 WebP files, see the savings per file, and download individually or as a ZIP. Processing happens in memory and files are deleted instantly.