Android App Modularization Strategy

Seongchul Park from Coupang reveals how they tamed a 300,000+ line monolithic Android codebase. The build times were spiraling, new features were getting tangled, and Google's modern deployment features were out of reach.

This is Part 2 of Coupang's Android architecture series, focusing on their modularization journey. As Korea's leading e-commerce platform expanded into new business areas, their single-module app became unsustainable. The team needed a systematic approach to break apart their monolith while maintaining stability.

Key Takeaways

• Split monolith into 3 module types: app, feature, and core modules
• Extracted 13 core modules with over 80% unit test coverage
• Core modules now reusable across multiple Coupang mobile projects
• Reduced inter-module dependencies through configuration injection patterns
• Enabled support for Instant Apps and App Bundles deployment

Part 3 reveals their repackaging strategy for eliminating stubborn dependencies that traditional modularization couldn't solve.