What is a VDEX file? A VDEX file is created by the Android operating system to speed up the load time of an Android app ( .APK file). It contains pre-validated .DEX files, which Android does not need to re-extract and re-verify when recompiling an app.

More Information In 2019, Google introduced the VDEX file format. The VDEX format was another iteration in Google's attempts to optimize Android apps' compilation and loading process. When a user installs an Android app, Android automatically optimizes that app and creates a corresponding .OAT and VDEX file. Referencing these files, rather than recompiling apps upon each load or update, allows Android to load apps more quickly, creating a better user experience. VDEX files contain optimized versions of previously validated DEX (Dalvik Executable) files, which Android has noted that it does not need to re-extract and re-verify when recompiling an app. VDEX files are typically stored alongside OAT files, in an Android device's /​data/​dalvik-cache directory.