After downloading eclipse plugin for Java Decompiler from http://java-decompiler.github.io/ follow below steps Download JD-Eclipse ZIP file, Launch Eclipse, Click on "Help > Install New Software..." , Drag and drop ZIP file on dialog windows, Check "Java Decompiler Eclipse Plug-in" , Click on "Next" and "Finish" buttons, A warning dialog windows appear because "org.jd.ide.eclipse.plugin_x.y.z.jar" is not signed. Click on "Install anyway" button. Click on "Windows > Preferences " Search for "File Association" For "*.class" & "*.class without source" select Associate editor as "JD class file viewer". 👍