WinMerge is a freeware, Open Source project that helps you compare folders or files. You can also find differences between old and updated text files and merge them.
As a file comparer, WinMerge helps you find what has changed between text files, by highlighting them. Then using merge menu you can merge changes between versions. It can handle Windows, Unix and Mac text file formats, with unicode support, syntax highlighting, line numbers and word-wrap.
As a folder comparer, it has file filters allowing you to exclude and include items. You can compare a folder with or without it's subfolders and results can be shown in a tree-style view.
WinMerge can be used as an external differencing/merging tool or as a standalone application for Windows 98/Me/2000/XP/Vista/7.
In order to install the portable version of WinMerge. Download and run the self-extract "WinMergePortable_2.12.4.paf.exe" file. Then run "WinMergePortable.exe".