Android Developers Blog: Mercari reduces 355K lines of code, a 69% difference, by rebuilding with Jetpack Compose
Article Summary
Mercari just deleted 355,000 lines of code from their Android app. And it works better than ever.
When Mercari's 7-year-old codebase became a bottleneck for shipping features, they made a bold call: rewrite the entire Android app from scratch. They chose Jetpack Compose, Android's modern UI toolkit, for their complete rebuild across 130+ screens.
Key Takeaways
- Eliminated 355K lines of code (69% reduction) while maintaining full functionality
- Home screen renders frames up to 2x faster with baseline profiles
- Reduced slow rendering instances by 23.6% using Compose performance tools
- Rewrote 130+ UI screens with new design system fully integrated
- Used AndroidView for drag gestures before Compose APIs were available
Critical Insight
Mercari's complete rewrite with Jetpack Compose resulted in 69% less code, 2x faster rendering, and a more maintainable codebase that ships features faster.
