WinDiff is a graphical file comparison tool included with the Windows operating system. It enables users to compare the contents of two files or directories to highlight differences. This tool is especially useful in software development, where it helps in code review processes and verifying file version differences. It can also be used for comparing system configuration files or any text-based document.


The basic command structure for invoking WinDiff from the command line is:

windiff [options] [file1] [file2]

WinDiff can be used without options for a simple file comparison. For directory comparisons, specify the paths of the directories instead of files.


Graphical Interface

  • No specific command line options are needed to launch in the graphical mode. Simply start WinDiff with or without file paths.

Comparison Options

  • /T – Opens comparisons in a new window. Useful when comparing multiple sets of files simultaneously.
  • /S – Forces WinDiff to compare all subdirectories when comparing directories.
  • /D – Specifies that only differences should be shown. Matches are ignored.
  • /B – Ignores blanks (spaces and tabs) during the comparison.
  • /U – Uses Unicode comparison rules. Recommended for files with Unicode characters.
  • /I – Ignores the case of text in the files during comparison.


Compare Two Files

windiff file1.txt file2.txt

Compare Two Directories Including Subdirectories

windiff /S C:\directory1 C:\directory2

Compare Files Ignoring Case and Spaces

windiff /I /B file1.txt file2.txt

Common Issues

  • Encoding Differences: Files with different encodings might not compare correctly. Ensure both files have the same encoding.
  • Access Permissions: When comparing directories, make sure you have read permissions for all directories and files being compared.

Solution: Always check and match file encodings prior to comparison and ensure adequate permission levels are set.


WinDiff can be integrated with batch scripts for automated tasks. For example, comparing backup directories regularly:

@echo off
windiff /S "C:\backup\today" "C:\backup\yesterday" > diff_report.txt
if not errorlevel 1 echo No Differences Found! > status.txt

This script compares today’s backup with yesterday’s, outputting the results to a text file and creating a status indication file.

  • FC (File Compare): A command-line tool that performs a line-by-line comparison of two files.
  • COMP: Another command-line tool used to compare the contents of two files or sets of files byte-by-byte.

For more detailed information on file comparison tools, consult the official Microsoft Documentation.