Nitro Pro - An affordable Adobe Acrobat alternative for editing and creating PDF
Beyond Compare - Beyond Compare allows you to compare files and folders.
Adobe Acrobat DC - Make your job easier with Adobe Acrobat DC, the trusted PDF creator. Use Acrobat to convert, edit and sign PDF files at your desk or on the go.
WinMerge - WinMerge is an open source differencing and merging tool for Windows.
PDF-XChange Editor - The smallest, fastest, most feature-rich PDF editor/viewer available
Meld - What is Meld? Meld is a visual diff and merge tool targeted at developers.