How to Compress a PDF Without Ruining It
Why PDFs get big
Scans and photos are the usual cause. A page stored as a high resolution image can be several megabytes, while a page of plain text is a few kilobytes.
Step 1: Optimize
Optimize rewrites the file more efficiently without touching what you see. It is lossless and keeps text selectable. It helps most with files produced by some exporters, and less with scans.
Step 2: Smaller file
If you still need a smaller file, choose Smaller file. Each page is turned into an image at the quality you pick and the PDF is rebuilt. Scans and image heavy documents shrink a lot. The trade off is that text is no longer selectable or searchable.
Compare before you send
The tool shows the size before and after, and only offers the download if the result is smaller. Open the result and check that small print is still readable.
Other ways to shrink a file
Split a large PDF into parts, or remove pages you do not need with the editor.