Smali

Smali is an assembler for the Dalvik bytecode used by the Android runtime (Dalvik and ART). It provides a human-readable representation of DEX instructions, enabling the construction and modification of Android applications at the bytecode level. The corresponding disassembler Baksmali performs the inverse operation, translating DEX back into Smali.

Smali is widely used in reverse engineering, security analysis, and app modification workflows. A common workflow is to disassemble a dex file to Smali using baksmali, edit the Smali code, and reassemble it into a Dex file with smali for re-packaging and re-signing applications. This makes Smali a central component in many toolchains that inspect or alter Android apps, such as Apktool.

Smali syntax resembles assembly language and focuses on the low-level structure of Android classes and methods. It uses registers (for example v0, v1, etc.), labels, and directives such as .class, .super, .method, and .field to describe class definitions, method bodies, and field declarations. Smali files typically carry the .smali extension and serve as the human-readable representation of Dex bytecode.

History and ecosystem: Smali originated within the Android reverse-engineering community and is maintained as an open-source project. It is widely used alongside Baksmali and Apktool, and compatible with other Dex-related tooling. While powerful for analysis, patching, and research, working with Smali and Dex involves legal and policy considerations regarding the modification and redistribution of applications.