WinMerge is a Windows tool for visual difference display and merging, for both files and directories. It is highly useful for determining what has changed between file versions, and then merging those changes. WinMerge has Unicode support, Flexible syntax coloring editor, Visual SourceSafe integration, and Windows Shell integration. Regexp filtering for filenames and lines. Side-by-side line difference and highlights differences inside lines. A file map shows the overall file differences in a location pane. The user interface is translated into several languages. 

WinMerge is an Open Source differencing and merging tool for Windows. WinMerge can compare both folders and files, presenting differences in a visual text format that is easy to understand and handle.

WinMerge is highly useful for determining what has changed between project versions, and then merging changes between versions. WinMerge can be used as an external differencing/merging tool or as a standalone application.

In addition, WinMerge has many helpful supporting features that make comparing, synchronising, and merging as easy and useful as possible. Several programming languages and other file formats are syntax-highlighted.

WinMerge is not a hex editor. WinMerge can show binary files contents and differences between them. But the information is meant for viewing only: editing binary files with WinMerge can break the files.

The goal of WinMerge development is to make comparing, synchronizing, and merging folders and files easy and fast, while maintaining maximum reliability. Ease of use is of key importance for reducing errors. The latest version, 2.14 is considered a stable and reliable program to use.

WinMerge is highly useful for determining what has changed between project versions, and then merging changes between versions. WinMerge can be used as an external differencing/merging tool or as a standalone application. 

In addition, WinMerge has many helpful supporting features that make comparing, synchronising, and merging as easy and useful as possible: 

General 

• Supports Microsoft Windows XP or newer 
• Handles Windows, Unix and Mac text file formats 
• Unicode support 
• Tabbed interface 

File Compare 

• 3-way File Comparison New! 
• Visual differencing and merging of text files 
• Flexible editor with syntax highlighting, line numbers and word-wrap 
• Highlights differences inside lines 

• Difference pane shows current difference in two vertical panes 
• Location pane shows map of files compared 
• Moved lines detection 

Folder Compare 

• Regular Expression based file filters allow excluding and including items 

• Fast compare using file sizes and dates 
• Compares one folder or includes all subfolders 
• Can show folder compare results in a tree-style view 
• 3-way Folder Comparison Work in progress 

Image Compare New! 

• Support many types of images 
• Can highlight the differences with blocks 
• Overlaying of the pictures is possible 

Version Control 

• Creates patch files (Normal-, Context- and Unified formats) 

• Resolve conflict files 

How to Use WinDiff to Compare Registry Files 

 To compare two files by using Windiff.exe, follow these steps: 
 

Start Windiff.exe. 

On the File menu, click Compare Files. 

In the Select First File dialog box, locate and then click a file name for the first file in the comparison, and then click Open. 

In the Select Second File dialog box, locate and then click a file name for the second file in the comparison, and then click Open.

The information in the right pane indicates whether there is a file difference. 

To view the actual file differences, click the first line in the Windiff.exe output results, and then on the Expandmenu, click Left File Only, Right File Only, or Both Files.

The color-coded results indicate what the file differences are. 

To compare two folders by using Windiff.exe, follow these steps:
 

Start Windiff.exe. 

On the File menu, click Compare Directories. 

In the Select Directories dialog box, type the two folder names that you want to compare in the Dir1 and
Dir2 boxes. If you want to include subfolders, click to select the Include subdirectories check box.

The information in the right pane indicates the differences between the two folders. 

To view the actual file differences, click the line that you want in the Windiff.exe output results, and then on the
Expand menu, click Left File Only,
Right File Only or Both Files.

The color-coded results indicate what the file differences are. 

You can also run Windiff.exe from the command line. For information about how to do so, or for more information about how to use Windiff.exe, see the Windiff.exe Help file (Windiff.hlp).

There are other utilities that are available besides Windiff.exe that you can use to compare local ASCII and binary files, or to compare a local file to a questionable file at a remote site.

To compare two files or groups of files at a local site, you can use the Fc.exe and the Comp.exe file compare commands. Both commands are run from a command prompt.

You can use Fc.exe to compare two ASCII or binary files on a line-by-line basis. It offers several command-line options. For example, use the fc /b command to compare two binary files. For a complete list of options, type fc /? at a command prompt.

You can use Comp.exe to compare ASCII and binary files and to compare groups of files in two different folders. For example, to compare all the .dll files in one folder to all the .dll files in the same folder on a different computer, type the following at a command prompt: 

comp C:\Winnt\System32\*.dll \\DifferentComputerName\C$\Winnt\System32\*.dll
 

To compare a local file to a remote file, you can use a utility such as the third-party compression utility Pkzip.exe. To do so, use Pkzip.exe to zip the file at both the local and the remote sites. Because zipping a large file can take time, it is faster to use the pkzip -e0 (no compression) option. After you have zipped the files, use the
pkzip -v command to examine the cyclic redundancy check (CRC32) value for the .zip files. If the CRC32 values are the same for the remote and local sites, the files are the same.

Note If you use Pkzip.exe to zip a file before you send the file to a remote site, because of the embedded CRC32, you will receive an error message during the unzip process if the file is damaged in transit. If you receive no error message, the file was conveyed without damage. 

Major Features of WinMerge:

In addition, WinMerge has many helpful supporting features that make comparing, synchronising, and merging as easy and useful as possible:

• General
  • Supports Microsoft Windows 2000/XP/2003/Vista/2008/7/8/2012
  • Handles Windows, Unix and Mac text file formats
  • Unicode support
  • Tabbed interface
• File Compare
  • Visual differencing and merging of text files
  • Flexible editor with syntax highlighting, line numbers and word-wrap
  • Highlights differences inside lines
  • Difference pane shows current difference in two vertical panes
  • Location pane shows map of files compared
  • Moved lines detection
• Folder Compare
  • Regular Expression based file filters allow excluding and including items
  • Fast compare using file sizes and dates
  • Compares one folder or includes all subfolders
  • Can show folder compare results in a tree-style view
• Version Control
  • Creates patch files (Normal-, Context- and Unified formats)
  • Resolve conflict files
  • Rudimentary Visual SourceSafe and Rational ClearCase integration
• Other
  • Shell Integration (supports 64-bit Windows versions)
  • Archive file support using 7-Zip
  • Plugin support
  • Localizable interface
  • Online manual and installed HTML Help manual