VisiPics - VisiPics does more than just look for identical files, it goes beyond checksums to look for similar...
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.
dupeGuru - dupeGuru is a tool for finding duplicate files on your computer.
Foxit Reader - Foxit Reader is a free and light-weight multi-platform PDF document viewer.
Pixiple - Find images similar in pixel and/or metadata content
Wondershare PDFelement - All-in-one PDF editor