Fernflower is a really nice Java decompiler. It’s pretty convenient since you can decompile the whole JAR file. And as far as I see the code is more clean in comparison to JAD. The usage of it is really straightforward: java -jar fernflower.jar mms-stubs.jar mms-stubs-sources.jar As a result you get mms-stubs-sources.jar with the decompiled sources. Will use this decompiler as the default one to see any possible issues and to compare it against my default JAD.