This is an old version of WinMerge, for the latest version go to the download page.
Screenshots
File compare window is basically two files opened to editor into two horizontal panes. Editing allows user to easily do small changes without need to open files to other editor or development environment.
WinMerge allows selecting/opening paths in several ways. Using the Open-dialog is just one of them.
Statuspane always shows current status of compare so it can be used to verify there are no different files left to handle.
Directory compare shows all files and subdirectries found from compared directories as list. Directory compare allows synchronising directories by copying and deleting files and subdirectories. Directory compare view can be versatile customised.
Many times it is useful to see exact differences inside lines. WinMerge can highlight different area between lines.