The Fundamentals of iOS Development at Revolut

Illia Kucheriavyi from Revolut reveals how 120+ iOS engineers ship weekly releases across 5 apps while maintaining 150,000+ automated tests. Their secret? A mono-repo with 160 shared modules and build times that dropped from 40 to 10 minutes.

Revolut's iOS team manages multiple financial apps serving millions of users with weekly App Store updates. They've built an engineering culture around speed and quality, using modular architecture, feature flags, and custom tooling to deliver continuously without sacrificing reliability.

Key Takeaways

• 2,200 monthly PRs generate 4,000+ CI builds with 10-minute validation times
• Mono-repo houses 160 shared modules across 5 apps, each buildable independently
• 12,000 unit test suites with 150,000+ test cases plus 3,000 UI tests
• Switched to Bazel for cloud caching, cutting CI time by 75%
• Cross-functional teams own modules end-to-end with no dedicated QA engineers

The article details their custom feature flagging framework and experimentation platform that lets them test ideas with statistical significance before full rollout.