When I go to C:\Users\(user)\AppData\Roaming\.minecraft\versions\1.6.2, I see my .jar file but when I try to open it, it does nothing. So how do I open my .jar file so I can mod it? I also know that if I extract the files my minecraft crashes. Why is that? How can I open it so I can mod it?

  • How do you open it? Do you double-click it, or right click > Open with > Editor?
    – 5pike
    Commented Oct 11, 2013 at 6:26
  • 1
    @5pike Not always possible. Most jar files do not have editable code in it, but precompiled one to save you time when compiling your project. Then there is again the difference between access to the jar file's functions and methods and a pure executable jar file. To Raymond Green: I think most people take the byte code which is interpreted by the Java virtual machine and from there on decompile the jar file into somewhat readable code. Problem beeing that classes,variables, etc are not named as in the original code. This is just an educated guess though, so I'm not posting this as an answer.
    – Strike
    Commented Oct 11, 2013 at 7:25
  • Also, I think this question might be better answered by gamedev.stackexchange.com as it deals with a game-specific programming issue.
    – Strike
    Commented Oct 11, 2013 at 7:34
  • @strike No, they're not trying to create mods (you can't do that by opening the jar). They're trying to install mods as an end user. Commented Oct 11, 2013 at 15:10

1 Answer 1


you use any package manager that can handle a zip, because a jar is a zip with a different extension, the jar is signed though so you'll need to remove the files in META-INF when you repackage

however I suggest you look at forge; this is an api to make modding easier and allows compatibility between mods

  • 3
    7-zip is a good one.
    – Dillmo
    Commented Oct 11, 2013 at 13:07
  • @Dillmo Or WinRar.
    – John
    Commented May 15, 2019 at 9:17

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