Quick start

1. Selecting files and folders to compare

After you have installed WinMerge, step through the procedure and discussions in this topic to learn basic WinMerge operations and concepts. The methods shown are not the only ways to do things: there are usually several ways to do each task. When you are done, you can go on to learn other methods and more advanced skills, which are covered in other help topics.

1.1. Open the WinMerge window

Here are some of the methods you can use:

  • Double-click the WinMerge desktop shortcut.

  • Navigate to the WinMerge launcher in your Start menu.

  • In a Command Prompt window, cd to the WinMerge installation folder and enter WinMergeU.

  • Press Windows+R and enter winmerge.

1.2. Open the Select Files or Folders dialog

In the WinMerge window use the following methods to open the Select Files or Folders dialog:

  • Click FileOpen.

  • Click the WinMerge open button Open tool bar button.

  • Press Ctrl+O.

1.3.  The Select Files or Folders dialog

Select Files or Folders window

1.3.1. Specify the files and folders

In the 1st and 2nd fields, specify the files and folders to compare. Use any of these methods:

  • Enter the path names directly into the fields.

  • Click the Browse button to navigate to the desired path.

    In the Open dialog, the text, Folder Selection, is initially displayed in the File name field. Your selection depends on the type of comparison you want to do:

    • If you are comparing files, select the target file. The Folder Selection text is overwritten with your selection.

    • If you are comparing folders, open the target folder; do not select a file. The Folder Selection text remains in place.

    Click Open to dismiss the Open dialog and load your selection in the 1st or 2nd field. If you specified folders, the field includes a backslash ( \ ) at end of the path.

  • Click the combo box and choose a previously-used path.


    To make it easier to select frequently-used paths, consider enabling the Open-dialog Auto-completion option. With this option, WinMerge shows a list of paths available as you type in the fields. See Options and configuration for details.

  • Drag and drop a file or folder into the dialog or the 1st or 2nd field.


You can select only one pair of files or one pair of folders to compare. If you select a file and a folder or if one of the files or folders is not found, WinMerge disables the Compare button in the dialog.

The status message at the bottom of the dialog also informs you if one of the paths is invalid.

1.3.2. Control the scope of folder comparisons

If you are comparing folders, you can use the Filter field to eliminate some files from the operation. The field specifies a subset of files in the selected paths that are to be included; all unspecified files are excluded.

You can enter file masks to filter files with certain extensions. For example, this expression includes only C and C++ source files; all other file types are eliminated from your selection.


For more robust filtering, enter a filter file instead of file masks: click the Select button next to the Filters field to choose from a list of available filters. File filters contain any number of rules to either include or exclude files. WinMerge installs a set of filter files, which you can edit or augment with your own files.

See Using Filters for full details about file masks and filter files.

The Include Subfolders check box provides another way to control the scope of folder comparisons. If you check this option, WinMerge recursively compares subfolders, and shows all the files and folders it finds in one view. If you disable the option, only the current folder is compared, and subfolders are listed by name (without their contents), so you can browse into them.

1.3.3. Use Unpacker plugins

The Unpacker field enables you to perform compare operations on plug-ins.

1.4. Other ways to open files and folders

The Select Files or Folders dialog is the main interface for opening files and folders. But you can use many other ways, too:

2. Comparing folders

If you selected two folders in the Open dialog, the Folder Compare window is opened. The Folder Compare window is a tabular list of items found in the compared folders. Each row displays information about a found file, with the file name in the left column and additional information in the other columns:

Folder Compare window

WinMerge does not have a concept of original and changed sides. Instead, it simply shows what is different between two selected folders. A file or folder that is found only on one side is simply shown as a unique item on that side, not as added or removed. For example, in the Comparison result column of the preceding figure, Merge.aps and Merge.rc.bak are each found in only one of the compared folders.

You can manage files and folders in many ways using the Merge menu, toolbar buttons, or context (right-click) menu. The most important action is making files or folders identical in both sides by selecting one of several Copy items. When you copy a file or folder to other side, the Comparison result value changes to Identical.

If a file or folder exists in both sides (and it is not a binary file) it can be opened for file comparison using one of these methods:

  • Click CompareMerge in the WinMerge menu.
  • Right-click the row and choose the Compare shortcut.
  • Double-click the row.
  • Select the row and press Enter.

If you compare a subfolder, the new folder's comparison table is loaded in the current Folder Compare window . When you are done with that folder's comparison, you can navigate back to its parent folder by double-clicking the Navigator up arrow button up arrow at the top of the Filename column.

If you compare a file, WinMerge opens the File Compare window, described in the next section. If you change a file in the File Compare window, and then return to the Folder Compare window, you will see the file's data is updated there.

3. Comparing files

File Compare window

The File Compare window shows the two selected files side by side, in separate File panes. Different lines are highlighted with a background color. One or more consecutive different lines form one difference (or diff). In the preceding example, a single difference is selected in the File panes and displayed by itself in the Diff Pane. WinMerge mainly works with these differences, not separate lines. When you merge a difference, you copy all of its lines from one side to the other.


Notice how WinMerge fills missing lines, so that similar lines are always aligned vertically, side by side. This is different from most other compare/merge programs, and can take a while to learn.

WinMerge has a simple integrated editor that features basic typing, copying, cutting and pasting of text. If Automatic rescan is enabled, WinMerge updates file differences while you edit a file. If Automatic rescan is disabled, you can update files by selecting EditRefresh, clicking the Refresh button toolbar button, or pressing F5.