How Crop PDF pages works
PDF crop lets you visually trim the visible area of PDF pages by dragging a crop rectangle in the browser. You can apply the crop to a single page or to every page at once, useful for removing excessive margins, cutting off headers or footers, or standardising a document's visible area.
Cropping in PDF adjusts the CropBox of each page rather than discarding content: the hidden area remains in the file structure but is not displayed or printed. An "apply to all pages" option propagates the same CropBox across the whole document in a single drag-and-set.