AptDiff - AptDiff is a visual text / binary files comparison and merging utility for Windows.
WinDiff - Download Windiff : free files and folders comparison tool
GNU Diff Utilities - GNU Diffutils is a package of several programs related to finding differences between files.
Workshare Compare - Workshare Compare is the leading platform for comparing two documents for differences across all document types.
Text compare! - Text compare! is a online diff tool that allows you to easily spot the differences between to texts.
WinMerge - WinMerge is an open source differencing and merging tool for Windows.