For as long as Android has been around, Android apps have been launched in the APK format (which stands for Android Package). However, in 2018, Google introduced a new format called Android App Bundles, or AAB (with the filename *.aab). Google touted that this new format would result in smaller app file sizes and easier ways to control various aspects of apps. Of the millions of apps on the Google Play Store, thousands of them already use the AAB system.
Today, Google announced that the AAB format will now officially replace Android APKs. This means that starting in August of this year, all new apps submitted to the Google Play Store must come in the AAB format. Apps that are currently APKs can stay that way — at least for now.
No more Android APKs: Good news or bad news?
In the end, this is good news for the average consumer. Android App Bundles can be up to 15% smaller than Android APKs, for example. Developers will also have more control over how they distribute updates to apps, which will likely result in faster and more efficient app updates.
However, there are two significant issues with AABs. The first is that developers who want their apps to appear in other distribution channels — such as the Amazon App Store or Huawei’s App Gallery — will need to manually export APK versions of their apps. This won’t require much effort on the dev’s part, but it would mean that any developer who wanted their app to only appear on the Play Store would have that power. In those cases, end users would need to export AABs as Android APKs on their own, as *.aab files would not work on alternative stores.
The other issue is that developers will need to give Google their app signing key to export an AAB app as an APK. This gives Google quite a bit of power. The app signing key is basically proof that a specific developer created a specific app. While it’s unlikely Google would ever do so, it is possible that it could sign apps on behalf of a developer. It’s also possible that someone could gain access to this key and then sign apps for themselves. As such, some developers aren’t too keen on the App Bundle format.
The bottom line, though, is that all new Android apps on the Google Play Store will need to be AABs. There’s no way around it. This is a bold new direction away from Android APKs, but we’ll need to wait for the dust to settle before we draw any conclusions.
