Many of us need to compare files, text files, source code etc. quite often. If you are looking for a good free application that helps you compare differences in a file, here is a list of open source tools that help you compare differences in files. Beyond Compare is one the famous file comparison tools but it is not free. Here is what you need..
Diffuse (Open source/Free for Mac, Windows, Linux)
A nice tool to to compare files and merge effectively. Free to use.
WinMerge (Open Source/Free for Windows)
Another popular tool to compare files. Quite capable and tested by many.
KDiff (Open Source/Free for Mac, Windows, Linux)
KDE community tool for comparing and merging files.
Meld (Open Source/Free for Mac, Windows, Linux)
Mergely (Online tool)
Online tool to do the file comparison/merging.
Diff Checker (Online tool)
Web based online tool that is free online diff tool that gives you the text differences between two blocks of text.
Text Compare (Online tool)
Text Compare is an online diff tool that allows you to easily make a text comparison and find the differences between two texts.
DiffMerge (Open Source/Free for Mac, Windows, Linux)
Kompare (Open Source/Free for Linux)
Kompare is yet another graphical difference viewer that allows you to visualize changes to a file.