WinMerge - WinMerge is an open source differencing and merging tool for Windows.
AptDiff - AptDiff is a visual text / binary files comparison and merging utility for Windows.
Beyond Compare - Beyond Compare allows you to compare files and folders.
WinDiff - Download Windiff : free files and folders comparison tool
kdiff3 - KDiff3 is a file and directory diff and merge tool which compares and merges two or three text...
Online Text Compare - Online Text Compare tool allows you to compare two documents in different formats.