Screenshots and exported graphics arrive as PNG, which stores every pixel exactly and gets heavy quickly. Saving one as a JPG at 92% quality usually brings that down a long way, and the page prints the size before and after so you can see what it actually saved. Transparent areas are filled with white on the way, because JPG cannot store them.
This page loads no libraries at all. The work is done by the browser itself. Your file is read on your own machine and never sent anywhere. Open your browser’s network tab and watch while you use it.
They are filled with white before the picture is drawn, because JPG has no way of storing transparency. If those areas need to stay empty, use the PNG to WEBP tool instead. That one leaves them alone.
Not on this page. It is fixed at 92%, which is a high setting but still a lossy one. If you want to trade quality for a smaller file, the image compressor has a slider for exactly that.
For photographs, usually by a wide margin. A flat screenshot or a line drawing can come out no smaller, sometimes larger, because JPG is built for photographs rather than sharp edges. Both sizes are shown, so you can check instead of assuming.
No. One file per run. Drop a handful and only the first one is taken. Run it again for the next.
Everything here is free and works the same way, in your browser.
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