Thread:GandalftheTurquoise/@comment-26339514-20151214005324/@comment-27723099-20151214081359

Depends on how you want to open them.

If you simply want to see the files inside (mostly unreadable compiled java files, but the mod also has all the other assets in it) then you can use unzip software (.jar has the same format as .zip).

If you want to decompile the java code to read it, use a decompiler (for example jd-gui on the whole jar.

If you want to execute it, run it with java (eg. with the cmd/bash command ).