WinMerge is a tabbed, visual file differencing and merging tool. It’s primary use is determining changes between two text files, but includes tools for folder, image, and 3-way comparison. It comes with a built-in editor with syntax highlighting, line numbers, word-wrap, synchronized scrolling, and handles a variety of file formats.
An unofficial plugin (xdocdiff) is available to enable comparison functions for the text of Word, Excel, PDF, LibreOffice, RTF, and other file formats.
WinMerge Portable is a portable version of WinMerge from PortableApps. Alternatively, an outdated X-WinMerge is also available.