Dex2Jar is an open-source command-line toolset, pre-installed on Kali Linux at /usr/bin/d2j-dex2jar, designed for reverse engineering Android applications by converting Dalvik Executable (.dex) files into Java .class files, typically packaged as .jar archives. Developed by Panxiaobo (pxb1988) under the Apache 2.0 License, Dex2Jar facilitates the analysis of Android APKs by transforming compiled .dex code into a format readable by Java decompilers like JD-GUI. Ideal for cybersecurity researchers, ethical hackers, and Android developers, it supports malware analysis, vulnerability assessment, and app debugging.