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FindFileExtension by

Current version

FindFileExtension Latest version is

Main feature overview

FindFileExtension is a program to find files with a particular extension (type) on a disk/folder or share. The output of the program is stored in a CSV file and can be opened in Excel for further processing. Examples for use are:
  • Find all files with extension .doc on desktop computers and notebooks and then collect the resulting files on a network drive. This can quickly provide an overview of personal data files that are carried on notebooks (AVG/GDPR).
  • Find all executables installed in the user profile. There are programs bypassing the User Account Control (UAC) feature to bypass the administrator installation by installing software in the User profile.

Other features:
  • FindFileExtension requires no installation and configuration
  • Works with UNC paths (\\<server name>\<share name>)

FindFileExtension version is free.



The first version of FindFileExtension was designed to quickly find Outlook archives or different files on PC's and notebooks a corporate worldwide network. The program FindFileExtension can be used on the command prompt or in a scheduled batch file or log on script.


The program FindFileExtension is very easy to use, but very flexible. The small program runs quickly and the source folder can be on a local disk or network share on a file server. The resulting file FindFileExtension creates is a (unicode) CSV file. Every file found is listed together with its full path and file size. This makes it easy to find very large files.


The program FindFileExtension is licensed according to the EULA in the download. Read the EULA carefully before using the program. A recent copy can be downloaded here.


The program FindFileExtension has three case insensitive parameters.
  • Root folder
  • Extension
  • Output File (CSV file)

Getting Quick help on FindFileExtension

By starting FindFileExtension without parameters or with an error in the parameters, FindFileExtension will display its options and a simple example:
FindFileExtension help screen
FindFileExtension help screen.
The program FindFileExtension requires a folder path for the source files, a file extension (with dot) and a file name for storing the data. The source path can be a hard disk, a mapped disk ( "G:\PublicFiles"), or a UNC path (\\nlaalfs1\PublicFiles). The destination file is created or overwritten with Unicode data. The destination file can be on a hard disk, mapped disk, or an UNC path.


  1. Just run the program on a command line to see the quick help documentation.
    Start the program from the hard drive, for example from the folder "Batch":
  2. By including the call to the FindFileExtension program in the login script or GPO, all Outlook archives can be found on the C:\ disks of all the systems logged-on on the network and the information can be collected on a network disk.
    C:\Batch\FindFileExtension c:\ .pst \\nlaalfs1\PublicFiles\%UserName%_%ComputerName%.csv
    This gives the following output in the file that is called "Johan_PC00001. csv":
    c:\Users\johan\Documents\Outlook Files\Outlook Data File - Johan.pst;779264
  3. Processing the files for analysis:
    By means of the command line instruction FindStr, the files can be easily made suitable for analysis. Go to the folder from the preceding example and create a drive mapping or use the Net Use command to map an unused letter to the folder share.
    Net Use Y: \\nlaalfs1\PublicFiles
    Now use the FindStr command to search all files on the PST extension:
    Y:\FindStr /i pst *.csv >> Analyse.txt
    This creates an analysis.txt file with the following content:
    Johan_PC00001.csv:c:\Users\johan\Documents\Outlook Files\Outlook Data File - Johan.pst;779264
    Paul_PC00002.csv:c:\Users\Paul\Documents\Outlook Files\Outlook Data File - Paul.pst;87265388
    George_PC00003.csv:c:\Users\George\Documents\Outlook Files\Outlook Data File - George.pst;6453782
    By using the "Text to table" function in Excel using the separators underscore "_", colon ":" and semicolon ";", the data is easily filtered to the next result.
    FindFileExtension Excel example
    FindFileExtension Excel example.
  4. To find executables in a user profile, add the following to your login script
    C:\Batch\FindFileExtension c:\users\%UserName%\ .exe \\nlaalfs1\PublicFiles\%UserName%_%ComputerName%.csv

Previous Releases

The following table shows the history of the FindFileExtension project.
Version Properties
1.0 Initial version
Programmed in Microsoft C# .Net


Download, unzip and copy the program FindFileExtension anywhere you want on the disk.

System requirements

FindFileExtension is designed for the .NET platform with Microsoft C#. Therefore Microsoft .NET Framework 2.0 or newer is required.
Windows VersionRuns .Net 2.0Tested
Windows XPYesNo
Windows VistaYesNo
Windows 7YesYes
Windows 8.1YesNo
Windows 10YesYes
Windows Server 2008 SP2YesNo
Windows Server 2008 R2 SP1YesNo
Windows Server 2012YesNo
Windows Server 2012 R2YesNo
Windows Server 2016YesYes

Support matrix will only support the latest version of free software.


Upon clicking the "Start download process" button, you get to another web page where you have to agree to the End User License Agreement (EULA) before you can download the program FindFileExtension

Frequently Asked Questions (FAQ)

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Scripts and programming examples disclaimer

Unless stated otherwise, the script sources and programming examples provided are copyrighted freeware. You may modify them, as long as a reference to the original code and hyperlink to the source page is included in the modified code and documentation. However, it is not allowed to publish (copies of) scripts and programming examples on your own site, blog, vlog, or distribute them on paper or any other medium, without prior written consent.
Many of the techniques used in these scripts, including but not limited to modifying the registry or system files and settings, impose a risk of rendering the Operating System inoperable and loss of data. Make sure you have verified full backups and the associated restore software available before running any script or programming example. Use these scripts and programming examples entirely at your own risk. All liability claims against the author in relation to material or non-material losses caused by the use, misuse or non-use of the information provided, or the use of incorrect or incomplete information, are excluded. All content is subject to change and provided without obligation.
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