If you’ve got a locked-down PDF, you’re out of luck… unless you’ve got Tracker Software’s free PDF-Xchange Viewer. In addition to letting you mark up existing PDFs, ...

If you don’t want to spend $74 on PDF-XChange Pro 2012, be aware that you can find most of the features it offers over and above the $45 PDF-XChange Tools 4 elsewhere for free.

PDF-XChange Editor is one of the best free PDF editors, and a successor to the excellent PDF-Change Viewer. Its design has been totally overhauled, making it much clearer and easier to use.