Local-First App Development with Event Sourcing - A Functional Approach in Kotlin

Explore functional programming patterns and event sourcing techniques for building resilient local-first applications in this 22-minute conference talk from Lambda Days 2025. Learn how to develop applications that maintain local state to ensure reliable offline experiences, particularly valuable in environments with unreliable or expensive internet connectivity. Discover how Kotlin's functional programming capabilities enable scalable and resilient local-first architectures through practical examples from EIDU's learning platform, an educational application designed for use in low and middle-income countries. Examine event-driven architectures that support offline-first experiences while maintaining strong consistency during cloud synchronization, and understand the principles behind building applications that prioritize local data storage and processing over constant server connectivity.