PDF Comparator lets you quickly and conveniently compare two PDFs to one another. It's a real confidence builder if you are the person responsible for ensuring that those last minute revisions were made, and, equally importantly, that nothing else changed in the process!
The comparison is made using the Mac OS X PDF rendering engine. Unlike most other PDF comparison tools, PDF Comparator compares page by page, pixel by rendered pixel - just as the PDF will print. You can save easily the product's $125 (USD) price on one project!
OK, so you want to stamp your document. Maybe you need to give reviewers some advice about the document's status or sensitivity. This tip from author Ted Padova demonstrates how to add stamps with the Stamp Tool along with related comments.