An APKS file is an APK set archive generated by bundletool, a utility used for creating and managing Android App Bundles (.AAB files). The archive, which is a compressed .ZIP file, contains a set of .APK files that are split based on device characteristics such as architecture, language, screen density, and other device features. bundletool uses the files to install optimized versions of the app on devices based on the device profile.

Android developers use APKS files to test app bundles before uploading them to Google Play. After generating an APKS file from an AAB file, a developer can then create device-specific APKs and examine them or install them on test devices. bundletool provides many different command-line options for generating APKs and includes the option to code sign them as well. To generate an APKS file from an AAB file, use the following command: bundletool build-apks --bundle=/path/to/app.aab --output=/path/to/app.apks If you're a developer and have a connected device, you can install your app from the APKS file using the following command: bundletool install-apks --apks=app.apks NOTE: bundletool is the official tool that Gradle, Android Studio, and Google Play use for creating and converting Android App Bundles (AAB files) and deploying APKs to user devices.