ProGuard (software)

ProGuard is an open source command-line tool that shrinks, optimizes and obfuscates Java code. It is able to optimize bytecode as well as detect and remove unused instructions. ProGuard is free software and is distributed under the GNU General Public License, version 2.
ProGuard is distributed as part of the Android SDK and runs when building the application in release mode.
Features.
Obfuscation.
ProGuard obfuscates Java and Android programs by renaming classes, fields, and methods using meaningless names, making it harder to reverse-engineer the final application.
Optimization.
Besides removing unused instructions from the compiled bytecode, ProGuard optimizes it using techniques such as control flow analysis, data-flow analysis, partial evaluation, static single assignment, global value numbering, and liveness analysis.
ProGuard can remove many types of unused and duplicated code, perform over 200 peephole optimizations, reduce variable allocation, inline constant and short methods, simplify tail recursion calls, remove logging code, among others.