Tutorsbot

Online Kotlin Compiler

main
// Online Kotlin compiler to run Kotlin code in the browser.
// Write Kotlin code in this online editor — no JDK install needed.

class Greeter {
    fun greet() {
        println("Hello, Tutorsbot!")
    }
}

fun main() {
    val g = Greeter()
    g.greet()
}

Kotlin is the official language for Android development. Run Kotlin online — learn null safety, data classes, coroutines, and modern JVM development.

Free Online Kotlin Compiler — Kotlin in Your Browser

Run Kotlin online without installing the JDK, IntelliJ IDEA, or the Kotlin toolchain. This playground executes your code on a JVM-compatible sandbox in the cloud, so you can prototype a coroutine-based pipeline, test a sealed-class hierarchy, or rehearse a Kotlin interview question — all without a 500 MB toolchain download. The editor uses the same professional code editor used by millions of developers, so syntax highlighting matches your local IDE.

Kotlin Playground for Android and JVM Developers

Common use cases: prototype a coroutine using `launch` and `async`, test a `when` expression against a sealed-class hierarchy before using it in a production data layer, rehearse a Kotlin-specific interview question (null safety, scope functions, data classes vs value classes) in front of a hiring panel, or share a runnable snippet with a teammate. The compiler reports both Kotlin compile errors with line/column hints and the runtime output. For a guided path beyond playground experimentation, see Tutorsbot's Kotlin Training and Android Development Training programmes.

Modern Kotlin Features Supported

Kotlin with the full language: coroutines (`launch`, `async`, `Flow`), sealed classes, `when` expressions, data classes, object expressions, extension functions, scope functions (`let`, `run`, `with`, `apply`, `also`), null safety (`?.`, `?:`, `!!`), generics with declaration-site variance, and inline classes. The standard library is fully available: `kotlin.collections`, `kotlin.sequences`, `kotlin.ranges`, `kotlinx.coroutines`. JVM-targeted compilation runs in a sandbox with most JDK APIs available.

Is the Online Kotlin Compiler Free?

Yes — 100% free for evaluation, learning, and interview preparation. No account, no captcha, no per-day limit. For production features (multi-file Gradle projects, Android-targeted compilation, persistent repls, scheduled jobs), see Tutorsbot's Kotlin Training and Android Training programmes.

What This Kotlin Playground Covers

The compiler runs Kotlin targeting a modern JVM with the full Kotlin and Java standard libraries bundled: `kotlin.collections`, `kotlin.io`, `kotlin.text`, `kotlin.sequences`, plus the entire `java.util.stream` and `java.util.concurrent` families. Coroutines (`kotlinx.coroutines`), data classes, sealed classes, extension functions, scope functions (`let`, `apply`, `also`, `run`, `with`), destructuring declarations, and string templates all work. What is NOT supported: Kotlin/JS, Kotlin/Native, Kotlin Multiplatform, and Gradle (no `kotlinx.serialization`, no `ktor`, no `arrow`). Multi-file projects are not supported; concatenate into a single file.

Why use the Kotlin online compiler?

  • Kotlin — coroutines, sealed classes, when expressions, data classes, extension functions
  • Standard library: collections, sequences, ranges, coroutines
  • JVM-targeted compilation in a sandboxed cloud environment
  • Compile errors with line/column mapping in the Output panel
  • Persistent workspace with autosave to localStorage

Frequently Asked Questions

Is the Kotlin online compiler free?
Yes — Tutorsbot's Kotlin compiler is completely free. No account required, no installation, and no usage limits.
Do I need to install Kotlin?
No. The Kotlin compiler runs entirely in your browser. No runtime, no SDK, no PATH configuration. Open the page and start coding.
Is my Kotlin code saved between sessions?
Yes — your code autosaves to your browser's local storage so you can resume where you left off. You can also generate a shareable URL.
Can I share Kotlin code with others?
Yes. Click the Share button to copy a URL that encodes your script. Anyone with the link can open and run it instantly — no account required on their end.
Is the Kotlin compiler safe to use?
Absolutely. Every program runs in an isolated sandbox. Your local system is never exposed to the executed code, and nothing is persisted after the execution window.