> For the complete documentation index, see [llms.txt](https://sallam.gitbook.io/sec-88/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://sallam.gitbook.io/sec-88/android-appsec/apk-structure.md). # APK structure 1. **META-INF**: Contains verification information like CERT.SF, CERT.RSA, and MANIFEST.MF files, which ensure app integrity and require resigning if any modifications occur. 2. **assets**: Stores developer-controlled resources such as videos, document templates, or code/data for frameworks like Cordova or React-native. 3. **AndroidManifest.xml**: A critical file that describes the app’s components, permissions, and compatibility features. This file is often modified during Appdome’s Fusion process to support selected settings. 4. **classes.dex**: Contains compiled Java/Kotlin code in Dalvik bytecode format. Multiple classes.dex files can exist if needed. Appdome adds and modifies these files during its Fusion process for policy integration and code obfuscation. 5. **kotlin**: Holds Kotlin-specific data if the app is written in Kotlin, which may change based on the Fusion policy. 6. **lib**: Contains native libraries for various processors (e.g., ARM, x86). The presence of these subfolders indicates platform compatibility. Appdome encrypts these files for security. 7. **res**: Contains resources with a predefined hierarchy for different screen orientations, OS versions, and languages. Appdome repacks these files during the Fusion process, often adding new files or altering existing ones. 8. **resources.arsc**: Links code to resources, facilitating the display of appropriate text or assets based on device settings. This file is also repacked by Appdome.