What is best way to compare pdf files side-by-side and show the modifications between the two?

I'm looking for windows software to do this It'd be great if you could post free and non-free products

Best Answer

On Linux and Windows you can use diffpdf (which differs from diff-pdf mentioned in this thread).

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Installing ubuntu using

sudo apt-get install diffpdf

See further this UbuntuGeek page on comparing pds textually or visually .

For Windows , this Diffpdf Windows version works really great. You can download from http://soft.rubypdf.com/software/diffpdf (scroll down to Win32 static version ).