Programming Languages
Kotlin Playground
Kotlin - compiled and run on JetBrains' server (the only non-browser runner).
Runtime: JetBrains public compiler service
api.kotlinlang.org) and results stream back. Prefer the full IDE-style experience? Open in official Kotlin playground →About this playground
Kotlin's compiler is JVM-based and cannot run in a browser, so this playground is the one exception on the site to our "nothing leaves your machine" rule. When you click Run, your code is sent to JetBrains' public compilation service (api.kotlinlang.org) and the output streams back. For the full editor experience with completions and diagnostics, use JetBrains' official playground at play.kotlinlang.org.
FAQs
Why isn't this fully in-browser?
Kotlin's compiler is written in Java and requires a JVM. There's no browser build of kotlinc today. All "try Kotlin online" tools (including JetBrains' own) work by shipping code to a server.
Where does my code go?
To api.kotlinlang.org, JetBrains' public compilation service. It's the same backend the official Kotlin Playground uses.
Is that safe?
It's a public service maintained by JetBrains for the Kotlin community, subject to their terms. Don't paste secrets or private code - treat it like any public online compiler.
Kotlin version?
Whatever JetBrains' service is currently serving - typically the latest stable Kotlin release, updated by them a few times a year.