DiffMerge is described as 'graphical file comparison program for Windows, Mac OS X and Unix, published by SourceGear' and is an app in the File Management category. There are more than 25 alternatives to DiffMerge for a variety of platforms, including Windows, Mac, Linux, Online / Web-based and BSD. The best alternative is Meld, which is both free and Open Source. Other great apps like DiffMerge are WinMerge (Free, Open Source), Beyond Compare (Paid), KDiff3 (Free, Open Source) and Diffinity (Free).
Beyond Compare allows you to compare files and folders. By using simple, powerful commands you can focus on the differences you're interested in and ignore those you're not. You can then merge the changes, synchronize your files, and generate reports for your records.
Diffinity is a diff and merging tool with focus on accurate and easy to read source code diffs. It will compare the content of two files and present the differences in an easy to read line by line and char by char basis.
WinMerge 2011 series is a fork of the original WinMerge application that compiles without ATL/MFC dependencies to enable zero-budget developers to build WinMerge from sources using Visual C++ Express editions.