Tool

Simplify

Generic Android deobfuscator built on smalivm, a sandboxed Dalvik virtual machine that executes each method and records every possible register and class value along all execution paths, taking both branches when a value such as file or network input is unknown. Simplify then repeatedly applies constant propagation, dead-code removal, unreflection and peephole optimizations to the APK or DEX, which can decrypt strings and remove reflection while keeping behaviour the same; it does not rename classes or methods. smalivm can also be used as a library, and the last release adds sdbg, a step-through Smali debugger built on it.

Targets: App
Category: Android tools
Relationship: Foundation tool
Sources reviewed: 2026-10-19

Requirements & limits

Development is inactive: the latest release, v1.3.0 of 2020-03-30, ships simplify, smalivm and sdbg jars, and the reviewed master commit dates from 2021-05-23. The project pins smali/dexlib2 2.4.0 and, by default, builds its Android framework reference from android-25 classes, so check results on apps that use newer DEX or API features.
Run it as java -jar simplify.jar on a user-supplied APK or DEX. Building needs JDK 8, a recursive clone for the AndroidFrameworkSmali submodule of reference framework classes, and the Gradle fatjar task. Execution limits on visits, call depth and time apply per method; the README advises narrowing large apps with include and exclude patterns, and output DEX defaults to API level 15.
--remove-weak, on by default, removes code even when it has weak side effects, and --ignore-errors may lead to unexpected behaviour, so compare output with the original code. The repository includes a project-provided obfuscated example app for testing; tests ran through a Travis CI configuration using Oracle JDK 8, the repository has no GitHub Actions workflow.
Dual-licensed: GPL-3.0 for open-source use, or a commercial license that permits binary distribution without source redistribution. Android framework classes and dependencies keep their own terms.

About this entry

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Primary sources

README.md GitHub · CalebFenton/simplify · Revision 29fb25d
LICENSE.GPL GitHub · CalebFenton/simplify · Revision 29fb25d
LICENSE.COMMERCIAL GitHub · CalebFenton/simplify · Revision 29fb25d
.gitmodules GitHub · CalebFenton/simplify · Revision 29fb25d
.travis.yml GitHub · CalebFenton/simplify · Revision 29fb25d
smalivm/build.gradle GitHub · CalebFenton/simplify · Revision 29fb25d
https://github.com/CalebFenton/simplify/releases/tag/v1.3.0

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