What is AAB?

AAB (Android App Bundle) is Google's publishing format for Android apps on Play Store. Unlike APK which is installable directly, AAB is a publishing format containing all app code and resources for all device configurations. Google Play uses AAB to generate optimized APKs for each device's specific screen density, CPU architecture, and language - users download only what they need. Results in 35-65% smaller downloads. AAB supports Play Feature Delivery, Play Asset Delivery, and dynamic modules.

AAB became mandatory for new apps on Google Play Store in August 2021. All major Android apps now use AAB: Facebook, Instagram, WhatsApp, TikTok, and millions of others. Developers build AAB with Android Studio and upload to Play Console - Play Store handles APK generation. AAB enables advanced features like on-demand module delivery, instant apps, and better app size management. Cannot be installed directly on devices (unlike APK) - requires Play Store or bundletool for testing.

Did you know? AAB reduces app download sizes by up to 65% compared to universal APKs!

History

Google developed Android App Bundle to solve the problem of large, universal APKs containing resources for all device configurations that users didn't need.

Key Milestones

  • 2018: Android App Bundle announced (Google I/O)
  • 2019: Play Feature Delivery introduced
  • 2020: Play Asset Delivery added
  • 2021: AAB mandatory for new apps
  • 2022: 1M+ apps using AAB
  • Present: Play Store standard

Key Features

Core Capabilities

  • Dynamic Delivery: Device-optimized APKs
  • Smaller Downloads: 35-65% size reduction
  • Feature Modules: On-demand delivery
  • Asset Packs: Large asset management
  • Instant Apps: No-install experiences
  • App Signing: Play App Signing integration

Common Use Cases

Play Store

All new app submissions

Games

Asset delivery optimization

Large Apps

Size reduction critical

Modular Apps

Feature-on-demand

Advantages

  • Dramatically smaller app downloads (up to 65%)
  • Device-specific APK optimization
  • Dynamic feature delivery
  • Play Asset Delivery for large files
  • Reduced user data usage
  • Higher conversion rates (smaller size)
  • Play Store mandatory standard

Disadvantages

  • Cannot install directly (not like APK)
  • Requires Play Store or bundletool
  • More complex testing workflow
  • Play App Signing required
  • Not suitable for third-party stores
  • Developer control reduced (Google generates APKs)

Technical Information

Format Specifications

Specification Details
File Extension .aab
Base Format ZIP archive
Contents Modules, resources for all configs
Size Reduction 35-65% vs universal APK
Max Size 150 MB (compressed AAB)
Distribution Google Play Store only

Common Tools

  • Development: Android Studio (Build > Generate Signed Bundle)
  • Testing: bundletool (generate APKs locally)
  • Publishing: Play Console (upload AAB)
  • Analysis: bundletool size-analyzer, Play Console app size reports