Android Developers Should Start Focusing On 'Android App Bundle' Than APK

Android App Bundle

When software becomes more complex, their size will grow. This is why optimization is needed to ensure things will run smoothly without necessary hiccups.

Android is known for its APKs, represented by their file installers that have the .apk extension. The format that stands for 'Android Package', which is a package file format that can be used on Android operating systems for distribution and installation of mobile apps, mobile games and middleware.

But knowing that app installation sizes have grown tremendously in order to include more and more features, Google said that developers should start optimizing their installers using Android App Bundles for publishing on its Play Store.

The search giant said beginning August 2021, the Google Play Console is going to require all new apps to publish with the Android App Bundle (.aab) format.

In a blog post, Google said that:

"In 2021, we are continuing with our annual target API level update, requiring new apps to target API level 30 (Android 11) in August and in November for all app updates. In addition, as announced earlier this year, Google Play will require new apps to use the Android App Bundle publishing format. This brings the benefits of smaller apps and simpler releases to more users and developers and supports ongoing investment in advanced distribution."
Android AAB

Google first introduced AAB as the alternative app distribution format at its 2018 I/O event, and later provided more details this August 2020.

According to Android on its developer post, AAB can optimize APK because:

"Google Play uses your app bundle to generate and serve optimized APKs for each device configuration, so only the code and resources that are needed for a specific device are downloaded to run your app. You no longer have to build, sign, and manage multiple APKs to optimize support for different devices, and users get smaller, more-optimized downloads."

In other words, AAB is a publishing format that includes all of an app’s compiled code and resources, and defers APK generation and signing to Google Play.

According to Android, most apps shouldn't require much effort to switch from APK to AAB.

"For example, if you already organize your app’s code and resources according to established conventions, simply build signed Android App Bundles using Android Studio or using the command line, and upload them to Google Play. Optimized APK serving then becomes an automatic benefit," said Android.

"When you use the app bundle format to publish your app, you can also optionally take advantage of Play Feature Delivery, which allows you to add feature modules to your app project."

Android AAB
The contents of an Android App Bundle with one base module, two dynamic feature modules, and two asset packs. (Credit: Android)

Previously, Android only suggested developers to upload their files using AAB if developers want to avoid using expansion files (OBBs) and if their app's compressed download size is larger than 100 MB.

This time, Google said that its Google Play Console will require all new apps to utilize Play Asset Delivery or Play Feature Delivery to deliver assets or features that exceed download size of 150MB, starting August 2021. Expansion files won't be supported for new apps.

Google said that the switch to Android App Bundle delivery should also impact instant experiences using legacy Instant app ZIP format. According to the company, starting August 2021, the new instant experiences and updates to existing instant experiences will be required to publish instant-enabled app bundles.

To entice the switch, Google said that at this time, more than 750,000 apps and games have started using AAB. Developers who switched, were capable of reducing their apps' installer size ranging between 15% to more than 50%.

For most users, they won't see anything much besides smaller app sizes and speedier downloads.

But for Android diehards and developers, they may struggle if they want to make app redistribution on other platforms. This is because AAB files are harder to manually sideload, which could cause some headaches to end users.