PDFs bloat for a common reason: repeated objects. A logo embedded on every page, a font referenced dozens of times, metadata nobody reads \u2014 each one written out again instead of shared. This tool rebuilds the file so those repeated pieces are stored once and packed efficiently, without touching a single pixel of the actual content.
It is a real, structural optimisation rather than a quality trade-off: the pages, images and text you see are identical before and after. How much smaller the file gets depends on how much redundancy was in the original.
