🧪 Kotlin – Compiler (Try Kotlin Online & Offline)
🧲 Introduction – Why Learn About the Kotlin Compiler?
The Kotlin compiler is the core tool that converts your .kt source code into executable files for different targets like JVM, JavaScript, or Native. Whether you’re building Android apps or experimenting with Kotlin on the web, understanding how to compile Kotlin code both online and offline is key to becoming a productive developer.
🎯 In this guide, you’ll learn:
- How the Kotlin compiler works and where to use it
- CLI installation and compilation process
- Online platforms where you can run Kotlin instantly
- Offline tools and advanced compiler options
⚙️ What Is the Kotlin Compiler?
The Kotlin compiler (kotlinc) is a command-line utility that takes Kotlin source files and compiles them into platform-specific binaries:
| Target | Output | Use Case |
|---|---|---|
| ☕ JVM | .class, .jar | Android, desktop, backend |
| 🌐 JS | .js | Web frontend with Kotlin/JS |
| 🖥️ Native | Executable | iOS, desktop, CLI tools |
The compiler is modular and supports REPL, scripting, multiplatform, and IDE integrations.
🌐 Kotlin Compiler – Online Platforms
You don’t need to install anything to run Kotlin code. Below are the top online compilers where you can try, test, and share Kotlin code instantly:
| Platform | Features |
|---|---|
| 🔗 Kotlin Playground | Official JetBrains editor with JVM/JS support, code sharing, coroutine support |
| 🔗 Replit Kotlin | Supports full projects with file structure, input/output, and team collaboration |
| 🔗 JDoodle – Kotlin | Quick code snippets, multi-language comparison, supports stdin |
| 🔗 OneCompiler – Kotlin | Fast execution, code history, built-in sample templates |
| 🔗 TutorialsPoint Kotlin Compiler | Educational platform with live execution, syntax highlights |
| 🔗 Paiza.IO | Simple and beginner-friendly interface with multiple language support |
✅ All these platforms allow you to:
- Run Kotlin code without setup
- Test syntax and output
- Share public or private code links
- Experiment with standard library functions
💻 Kotlin CLI – Offline Compiler Setup
If you prefer running Kotlin on your machine, install the compiler using:
✅ For Windows/macOS/Linux:
- kotlinlang.org
- Or use
brew install kotlin(macOS) or SDKMAN on Linux
🔍 Check Installation:
kotlinc -version
▶️ Compile and Run Locally
- Write a Kotlin file (
hello.kt):
fun main() {
println("Hello from offline Kotlin!")
}
- Compile to JAR:
kotlinc hello.kt -include-runtime -d hello.jar
- Run JAR file:
java -jar hello.jar
✅ Output:
Hello from offline Kotlin!
🧪 Kotlin REPL – Interactive CLI Testing
You can also launch the REPL shell using:
kotlinc-jvm
Then enter:
val name = "Kotlin"
println("Welcome, $name!")
📤 Output:
Welcome, Kotlin!
🧱 Advanced Compiler Options
| Option | Purpose |
|---|---|
kotlinc file.kt | Compile Kotlin to JVM class files |
kotlinc -script script.kts | Run Kotlin as a script (like Python) |
kotlinc-js file.kt -output out.js | Compile Kotlin to JavaScript |
kotlinc-native file.kt -o output | Build native apps (requires Native SDK) |
📌 Summary – Recap & Next Steps
You can use Kotlin both online via web compilers and offline via terminal or IDEs. Whether you’re just testing a snippet or building a full project, the Kotlin compiler offers flexibility for JVM, JavaScript, and Native platforms.
🔍 Key Takeaways:
- Use online platforms like Kotlin Playground or JDoodle to get started fast.
- Offline,
kotlincgives you full control over the compilation process. - REPL and scripting allow quick testing without full project setup.
⚙️ Practical Use:
Online compilers are ideal for beginners, quick demos, or interviews. Offline tools are better for production projects and integrated workflows.
❓ FAQs – Kotlin Compiler & Online Tools
❓ What is the best platform to run Kotlin online?
✅ The official Kotlin Playground offers the best features including Kotlin/JVM/JS support, coroutine support, and code sharing.
❓ Do I need to install anything to run Kotlin code?
✅ No. You can use platforms like Kotlin Playground or JDoodle directly in your browser without any installations.
❓ What is the difference between Kotlin REPL and online playgrounds?
✅ Kotlin REPL runs locally in your terminal and is part of the Kotlin CLI tool. Online playgrounds are web-based editors that compile remotely.
❓ Can I run Kotlin scripts like Python?
✅ Yes. Save your code as .kts and run it using: kotlinc -script myscript.kts
❓ Is Kotlin Playground suitable for mobile development?
✅ It’s best for testing logic and syntax, but full Android app development requires Android Studio or IntelliJ IDEA.
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