PDF work tends to fall into a few repeated tasks: combining several files into one document, pulling out just the pages you need, shrinking a file that's too large to email, or converting between PDF and image formats. This collection covers all of it without needing Adobe Acrobat or any paid software.
One thing worth knowing: PDF compression works by reducing image quality within the document and optimizing its internal structure — it won't meaningfully shrink a PDF that's mostly text, since text itself takes up very little space. If your PDF is large because of embedded images or scanned pages, compression will help significantly; if it's a text-heavy document that's still large, the file may have other issues worth checking, like unnecessarily high-resolution embedded fonts.
Merging and splitting are the two most common requests, and both matter for slightly different reasons — merging is typically about combining multiple scanned documents or reports into a single file to share, while splitting is more often about extracting one relevant section from a much larger document without sending the whole thing.