Total Commander - A Shareware file manager for Windows® 95/98/ME/NT/2000/XP/Vista/7, and Windows® 3.1.
Beyond Compare - Beyond Compare allows you to compare files and folders.
Double Commander - Double Commander is a cross-platform open source file manager with two panels side by side.
WinMerge - WinMerge is an open source differencing and merging tool for Windows.
XYplorer - File Manager for Windows
Meld - What is Meld? Meld is a visual diff and merge tool targeted at developers.