Reduce a PDF's file size by rebuilding its internal structure more efficiently. Works best on documents with a lot of repeated formatting; results vary on image-heavy scanned PDFs.
This tool rebuilds the PDF's internal object structure more efficiently (merging duplicate objects and using more compact internal storage), which meaningfully shrinks PDFs generated from Word, PowerPoint, or similar software with a lot of repeated formatting data. Being upfront about what it doesn't do: it does not re-compress or downsample embedded images, which is where most of the file size lives in scanned documents or photo-heavy PDFs. For a PDF that's mostly scanned pages, expect a modest reduction at best.
The most effective way to shrink an image-heavy PDF is to reduce the resolution of the images themselves before they become a PDF — for example, using PDF to Images, resizing those images with an image tool, then rebuilding with Images to PDF.