Google set to replace APK with Android App Bundles (AAB) Google appears to be making a significant change in the file formats of Android apps. Although apps have previously used the APK (Android Package) file format, Google has now announced that all apps will now be transitioned to the AAB (Android App Bundle) file format. The decision will empower developers to grasp how this improves their apps – reports indicate that all apps on the Google Android eco-system can now have up to 15 percent reduced file sizes. Large apps available at much smaller file sizes can be beneficial for users who are still on limited data networks, and this will result in faster downloads and lower storage requirements for end-users.