Definition
App Thinning is Apple's technology that reduces app download size by delivering only the code and resources needed for a specific device.
Why It Matters for ASO
App size is a critical conversion metric—smaller downloads drive higher install rates, especially on cellular networks or in bandwidth-constrained regions. App Store optimization algorithms favor apps with strong performance metrics, including reasonable file size, making app thinning a key lever for improving install-rate conversion and search visibility. By optimizing for maximum thinning, ASO practitioners reduce friction in the install funnel and improve cost-per-install metrics.
Key Points
- App Thinning reduces download size by 15–50% on average by excluding unnecessary assets and architecture-specific code for non-matching devices
- iOS App Store applies thinning automatically; developers optimize through proper asset cataloging, bitcode usage, and resource organization
- On-Demand Resources (ODR) and assetpacks enable dynamic feature delivery—users download additional content only when needed, further reducing install friction
- Larger apps face higher abandonment rates and weaker ranking signals; monitoring actual download size across device tiers informs ASO strategy
- Android equivalent: Google Play's Dynamic Delivery and App Bundle (available since 2018); both platforms reward lean apps with better visibility