I'd like to be able to examine the contents of a JAR file without having to install Winzip or some other tool and without having to rename the file. Windows Explorer can open ZIP files just fine; is there some registry setting I can use to let it treat JARs like ZIPs?

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    i wonder why this was migrated. why would anyone but a programmer be interested in this. Mar 22, 2010 at 17:45

5 Answers 5


Or from the command line:

assoc .jar=CompressedFolder

Under Vista (or higher) you have to run this in an elevated Command Prompt.

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    NB: for Vista and above, you'll probably need to run the command prompt with elevated privileges i.e. as Administrator.
    – Mal Ross
    May 25, 2010 at 12:45
  • works on Windows 8 as well +1. Thanks!
    – yair
    Nov 11, 2013 at 19:19
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    Also works on Windows 10 in CMD. Does not work in PowerShell. While you're doing this, I suggest you do it with .ear and .war, too. Mar 3, 2016 at 20:25
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    Also, assoc .jar=jarfile to restore
    – Numeron
    May 11, 2017 at 10:51

I tried exporting HKEY_CLASSES_ROOT\.zip, changing all references of '.zip' to '.jar' and importing it to HKEY_CLASSES_ROOT\.jar.

Under Vista at least it let me open a .jar file as if it were a .zip.


What you need to do is associate the JAR extension in Windows Explorer with Compressed folders. From Windows Explorer select tools / Folder Options. Then the Files Types tab. Select New and associate JAR Compressed (ZIP) Folder.


The HKEY_CLASSES_ROOT trick doesnt work under Windows 7. There mut be some compelling reason that MSFT doesnt want us to do this.

  • Worked fine for me under Windows 7.
    – Brannon
    Nov 30, 2009 at 4:29

In setting up a new Windows 10 machine this was the reason I used to install 7-zip but there is no need with this hack given by @hfrmobile.

  1. Press WinKey and type cmd
  2. Right click Command Prompt app and select Run as administrator
  3. Type assoc .jar=CompressedFolder, it should be echoed back to the screen if accepted otherwise you will get an access is denied
  4. Type assoc .ear=CompressedFolder
  5. Type assoc .war=CompressedFolder
  6. Right click a jar in Windows explorer and you should now see the Extract All... menu option available to zip files

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