Coupang Android Architecture Part 1

Joris Abale from Coupang reveals how they rescued a massive Android app drowning in God Activities and Fragment chaos. Their journey from architectural debt to 80% test coverage is a masterclass in pragmatic refactoring.

Coupang, one of Korea's most popular apps with 10 million users, faced a codebase crisis in 2016. Years of rapid feature development had created unmaintainable God Classes, complex fragment lifecycles, and mounting technical debt. The engineering team needed a systematic approach to modernize without disrupting their customer experience.

Key Takeaways

• Chose MVP over MVVM because Google's data binding was still beta
• Integrated SonarQube into CI pipeline to track code quality metrics
• Built custom MVP library to reduce boilerplate and ensure consistency
• Achieved 80% unit test coverage after months of systematic refactoring
• Adopted Google's lifecycle aware components when they launched in 2017

Part 2 reveals how they took modularization even further to handle their growing team and feature complexity.