What is Kotlin written in?
Kotlin is a general-purpose programming language derived from Java, first released in 2016.
Implementation
| Layer | Written in | Notes |
|---|---|---|
| Compiler | Java (since 2016) | Early Kotlin compiler written in Java before self-hosting |
| Compiler | Kotlin (since 2017) | Kotlin compiler became self-hosting; K2 frontend in 2024 |
| Runtime | Java (since 2011) | Kotlin runs on JVM |
Self-hosting
Kotlin is a self-hosting language: its compiler is written in Kotlin itself. Self-hosting means the compiler can compile its own source code, which is a milestone in a language's maturity. New versions of the compiler are built using an older version of the same compiler, a process called bootstrapping.
Self-hosting also acts as a practical stress test: if a language can compile its own compiler, most core language features have been validated in a complex, real-world workload. See what is compiler bootstrapping for a full explanation.
Explore in the Graph
See Kotlin's full lineage, including all implementation and influence relationships, in the interactive graph.
Open Interactive Graph →Or view the Kotlin language page for the complete record.