1)   Visual Patch 1.0.0.3
Provides software developers with a comprehensive solution for creating secure full-history software update patches. Visually indicates the differences among product releases and automatically builds only those changes into a single-file patch.
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 2)   DiffDog Professional Edition 2011
Altova DiffDog 2011 Enterprise Edition is a powerful diff/merge tool. This unique XML-aware sync utility compares files, folders, databases and XML Schemas. It indicates differences, intelligently merges content, and creates XSLT to convert XML data.
diff, diff/merge, differencing, database differencing, database comparison, database merging, diff files, diff source code, file comparison, file differencing,

 3)   DiffDog Standard Edition 2005
Altova DiffDog 2005 Standard Edition is the dedicated differencing utility for developers and power users. This easy, powerful synchronization tool quickly compares files and folders then highlights differences and merges content via an elegant GUI.
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 4)   WinMerge 2.4.6
WinMerge is a tool for visual difference display and merging, for both files and directories. Unicode support. Flexible syntax coloring editor. Windows Shell integration. Regexp filtering. Side-by-side line diff. Highlights differences inside lines.
diff, merge, text files, differencing, syncronize,