Create CSS sprite sheet

No. The conversion runs entirely in your browser. The file never leaves your device – there is no server that could see it. Once the page has loaded, the tool even works offline.

sprite.png with all images on a grid of equal cells (the largest width × the largest height), sprite.css with a base class and one class per image setting width, height and background-position, and sprite.json with the x/y/width/height of every sprite for build tools or games.

No, every icon keeps its exact pixels – sprites must be pixel-accurate. Icons of different sizes sit top-left in their cell; the CSS uses each icon's own width and height, so nothing else shows through.

In the order of the file list – the order you added them in. Remove and re-add a file to move it to the end. All files go into one result; drop a new set of files to start over.