You can use environment variables in your paths. Windows expands the variable name between % (percent) delimiters. For example, if an environment variable named WORKDIR has the value c:\workfiles, then the path %WORKDIR%\project1 is expanded to c:\workfiles\project1 .

WinMerge archive support is provided in the 7-Zip plugin. See Getting and installing WinMerge to install this plugin.

Opening two archive files is similar to opening normal files: specify two archive files in the Open-dialog's Left and Right fields. If WinMerge recognizes the archive format, it opens the contents of the archive files in the Folder Compare window.

The Comparing and merging folders topic describes how to work with archive files. For example, if an archive file contains two subfolders named Original/ and Altered/, you can compare the contents of the two subfolders by specifying the same archive file in both sides in the Select Files or Folders dialog or WinMerge command line.

The Filter edit field enables you to restrict the files to be included in your folder compare. You can specify one or more file masks, or a single file filter (not both).

A mask is a simple expression based on file extensions. For example, this list of file masks includes only files with the specified extensions; all others are excluded from the selection when the compare operation starts:

*.h;*.cpp *.txt,*.ini

File masks are practical for simple filtering; for more advanced selecting, use filter files. Filter files are collections of regular expressions that can either include or exclude files. WinMerge installs a number of predefined filter files in its Filters folder, and you can create your own, too.

To specify a filter, click the Select button next to the Filters field to choose from a list of available filters. Or, click the Filter drop-down list and choose a recently-used filter file.

For full information about filter masks and filter files, see Using Filters.

Unpackers are plugins that are installed with WinMerge to provide functionality that is not used by default. Plugins that can be used to preprocess certain types of files before comparing them. For example, WinMerge cannot normally compare MS Word doc files, but by unpacking them, you can compare just the text contents. See Plugins for details.

To apply a plugin to your file comparison, click the Select button for the Unpacker option. In the Select Unpacker dialog:

Your choice is displayed in the Unpacker field. Note that you cannot select an unpacker when launching a Folder Compare operation.

The advanced shell integration enables you to control the order in which paths are compared when you launch WinMerge from the Windows Explorer context menu. To configure the advanced shell integration, select Enable advanced menu in the System page of WinMerge options.

In the standard shell integration, when you select two paths in Windows Explorer and then right-click and choose WinMerge, the order of comparison in WinMerge is determined by the sort order in Windows Explorer. For example, if your Windows Explorer file list is sorted by name descending, and you select File1 and File2, WinMerge opens with File1 on the left side and File2 on the right. You can change the order only within WinMerge, after it opens.

The advanced shell integration replaces the standard WinMerge shortcut in the Windows Explorer context menu with a set of shortcuts that enable you to control the comparison order before launching WinMerge:

The shell integration paths that you map are stored in memory until you use them to open WinMerge. As a result, you don't need to select both files at the same time or even using the same Windows Explorer view: you can choose one, open a different directory, and choose the other one. Both paths are discarded from memory after a compare operation. This means that you cannot select one Compare To path and compare it against several paths.

Here is a simple method of using the advanced integration נthere are other scenarios, of course. In Windows Explorer:

By default, WinMerge does not include subfolders in compare operations. To change the default behavior, enable Include subfolders by default in the System page of WinMerge options. To change include subfolders while using the shell integration, press and hold the Control key while selecting Compare in the Windows Explorer context menu.

To use a project file In the WinMerge window, click File → Open Project. WinMerge reads the paths from the project file. If the project file has two paths, both paths are opened. If only one path is given or one of paths is invalid, WinMerge opens the Select Files or Folders dialog, where you can add or correct the path information. Here are a few things to consider:

To specify a project file on the command line, simply enter it as a single file path.

To save a project file, click File → Save Project. The Project File dialog provides fields and options that you can easily edit to build a project file. If a compare window is currently open, the Project File dialog is initialized with values from the current compare; otherwise, you provide the values yourself. To use an existing project, click Open and select a project to load its values (any existing values are overwritten in the dialog).

When you finished editing, click Save to store the file.

Project files are simple XML files with a .WinMerge extension. For example:

<?xml version='1.0' encoding='UTF-8'?>
<project>
   <paths>
      <left>c:\work\project1</left>
      <left-readonly>1</left-readonly>
      <right>c:\work\project2</right>
      <right-readonly>0</right-readonly>
      <filter>Visual C++ loose</filter>
      <subfolders>0</subfolders>
   </paths>
</project>

A project file contains a paths element that can contain one of each of these elements:

None of the fields is required, and they can be empty (for example, <left></left> or <left/>).