If you are using an online platform to convert your website into a mobile app, you will eventually be presented with a choice of which files to download: an APK or an AAB.
To a beginner, these acronyms can be confusing. Which one do you actually need? Do you need both?
In this article, we will explain the difference between APK vs AAB so you know exactly which file to use for your specific goals.
What is an APK? (Android Package Kit)
The APK is the traditional, historical file format for Android applications. It has been around since the very first version of Android.
An APK contains everything an app needs to run on any Android device. It contains the code, the images, and the layouts for every possible screen size and processor architecture.
What You Use an APK For:
Because an APK is a complete package, it can be installed directly onto a phone without the help of an app store.
- Testing: You download the APK to your own phone to test your new app.
- Direct Distribution: You host the APK on your website so users can download it directly (known as "sideloading").
- Internal Apps: Distributing private tools to your employees via email.
What is an AAB? (Android App Bundle)
The AAB is a newer publishing format introduced by Google.
Unlike an APK, an AAB cannot be installed directly onto a phone. Instead, an AAB is a massive publishing file that you give exclusively to the Google Play Store.
When a user taps "Download" on the Google Play Store, Google's servers look at the user's specific phone (e.g., a Samsung Galaxy S23). Google then takes your massive AAB file, extracts only the specific code and images needed for that exact Samsung phone, and generates a tiny, custom APK just for that user.
Why Google Created the AAB:
- Smaller App Sizes: Because Google only sends the exact files a specific phone needs, the final app size is drastically smaller (often 50% smaller) than a traditional APK. Smaller apps download faster and save space on the user's phone.
- Required for Publishing: As of August 2021, Google requires all new apps submitted to the Play Store to use the AAB format. They no longer accept APKs for new apps.
What You Use an AAB For:
- Publishing to Google Play: This is the only thing you use an AAB for. You take the AAB generated by your website-to-app converter and upload it to your Google Play Console.
Summary: Which One Do You Need?
The answer is: You probably need both.
- When you first generate your app, you need the APK so you can install it on your personal Android device and test that your website looks great in the app format.
- Once you are satisfied with your testing, you take the AAB and upload it to the Google Play Store so the rest of the world can download it.
If your online website-to-app converter only gives you an APK and refuses to give you an AAB, you will not be able to publish your app on the Google Play Store! Ensure you choose a platform that provides both formats.