A free, interactive online Kotlin course for beginners. You write and run real Kotlin in every lesson, get AI hints the moment you're stuck, and earn a free certificate when you finish - no Android Studio, no JDK, nothing to install.
- Declare immutable and mutable state with val, var, and type inference
- Handle nulls safely with ?. and the Elvis operator ?:
- Branch with if and when expressions and iterate with ranges and loops
- Write functions with default and named arguments and work with lists
