jPDF Tweak

jPDF Tweak is a free and open-source Windows application that lets you make all kinds of changes to any PDF document.

The application's features are organized into tabs. Each tab offers a different way to edit your document: change the page positions, add watermarks, compress multiple pages into one, change page numbers, and change bookmarks.

The application also lets you add attachments, extra information, encryption, and signatures. You can even add transitions between pages, which is great for presentations.

As you can see, jPDF Tweak is an incredibly comprehensive application with tons of features. It has a strong enough foundation to become a must-have application when it comes to editing PDFs.