Sinan Kozak

WORK HISTORY

EDUCATION

SKILLS

ABOUT SINAN KOZAK

I’m a Google Developer Expert and Staff Android Engineer passionate about crafting fast, stable, and scalable mobile experiences.For the past few years at Delivery Hero, I’ve been driving improvements across multiple Android applications that serve over 1 million riders in 70+ countries and millions of hungry users. My focus has been on performance, developer velocity, and architecture evolution — ensuring every line of code makes both the product and people better. What I’ve done:Boosted Application Quality Score (AQS) from -15 to 70+ through performance optimizations and architecture redesigns for rider application.Later I moved to customer application and moved Application Quality Score from 40 to 75 for different app.Reduced build times by 40+ minutes on average and cut flaky tests by 20% via smarter Gradle caching, lint automation, and CI/CD optimizations. Since then builds times are under 10 minutes per CI run on average.Drove startup time under 3s (P90) from 12 seconds and reduced frozen frames by 50% for rider app.When I moved customer app, I created moved proven approaches and reduced applications start up time by 5% in first month, later reduced frozen frame of main screen by 75%.Built a culture of ownership and mentorship, guiding engineers across teams while promoting cross-platform alignment (Android, iOS, Backend, Analytics).Spoke at Conference in Paris, Berlin, London, Turin and Lisbon on performance and Android improvements. I usually focus on architecture, build time improvements and runtime performance of apps.Contributed to open source (Compose Lint, Affected Module Plugin), fixing key issues that improved developer experience.I love connecting technical depth with organizational impact — from authoring RFCs and leading architecture reviews to mentoring engineers and shaping quality standards across teams.Currently part of Delivery Hero’s Mobile and Observability Experts Groups, I continue to explore new ways to make mobile systems faster, more reliable, and delightful to build.