App Size Reduction at Microsoft SwiftKey
Article Summary
Microsoft SwiftKey slashed their Android app size by 50% and boosted install conversions. Here's the playbook they used to get there.
The SwiftKey team documented their year-long journey reducing app bloat across 72 languages and 650+ keyboard layouts. They tackled everything from ProGuard configs to native libraries, sharing wins and head-scratchers along the way.
Key Takeaways
- Download size dropped 50% (27.6 MB to 14.3 MB) and install size fell 40%
- DEX code gets triple taxed: once in APK, again as VDEX, then as ODEX
- ProGuard config was accidentally disabling most optimizations for years
- Converting keyboard layouts to custom protobuf saved 6 MB alone
- Android App Bundles delivered 3 MB download and 18 MB install savings
Critical Insight
Small optimizations across ProGuard, native libraries, resources, and AABs compounded into massive size reductions that increased install conversions in key markets.
