WinDiff - Download Windiff : free files and folders comparison tool
Workshare Compare - Workshare Compare is the leading platform for comparing two documents for differences across all document types.
Online Text Compare - Online Text Compare tool allows you to compare two documents in different formats.
WinMerge - WinMerge is an open source differencing and merging tool for Windows.
GNU Diff Utilities - GNU Diffutils is a package of several programs related to finding differences between files.
Beyond Compare - Beyond Compare allows you to compare files and folders.