Online Kotlin Compiler
Write Kotlin in the browser and run it on our machines. The editor is opening.
Free online Kotlin compiler and editor
JDoodle is an online IDE that has served the programming community since 2013. You write, compile, and run code in the browser for Kotlin and many other languages, without installing a toolchain.
What you see on this page is JDoodle’s free Kotlin compiler. Write Kotlin in the editor, press Execute, and JDoodle runs it on its servers. You do not install Kotlin, and you do not need a JDoodle account to run code.
Online Kotlin editor
JDoodle’s Kotlin editor on this page highlights syntax, completes as you type, matches brackets, and folds blocks. It is an online Kotlin editor and a compiler together: you write here, then Execute runs your program on JDoodle’s servers.
Kotlin versions on JDoodle
JDoodle currently ships these Kotlin builds. Choose one from the version menu before you execute. The installed releases are 1.1.51 (JRE 9.0.1+11), 1.2.40 (JRE 10.0.1), 1.3.50 (JRE 11.0.4), 1.6.0 (JRE 17.0.1+12), 1.9.10 (JRE 17.0.1+12), and 2.3.10.
| Version |
|---|
| 1.1.51 (JRE 9.0.1+11) |
| 1.2.40 (JRE 10.0.1) |
| 1.3.50 (JRE 11.0.4) |
| 1.6.0 (JRE 17.0.1+12) |
| 1.9.10 (JRE 17.0.1+12) |
| 2.3.10 |
Maven libraries
JDoodle can pull public Maven packages into a Kotlin run. Add them in the library field, for example org.apache.commons:commons-lang3:3.4. Look up packages on search.maven.org. Private or local packages are not available on this JDoodle page.
Debugging Kotlin online
JDoodle debugs Kotlin in the browser, so you do not have to read a program and guess what it did. Set a breakpoint by clicking a line number, press Debug, and execution stops there. From that point you can step over a line, step into a call, step back out, or let it run on to the next breakpoint, and the call stack beside the editor shows how you arrived. Every local variable in the frame you are looking at is listed with its current value, and objects and arrays open up so you can look inside them. A debug session is interactive, so a program that reads input still reads it from you while it is paused.
Debugging runs on 2.3.10, the newest Kotlin build here and the one this page opens with. Older versions still compile and run as they always did, and the Debugger tab says so if you switch to one.
Debugging is free to use. Sessions last three minutes on the free plan and ten minutes on Pro and Teacher plans, and you can start as many as you need.
Frequently asked questions
Is JDoodle’s online Kotlin compiler free?
Yes. JDoodle lets you write and run Kotlin without paying. A JDoodle account is only needed to save projects, use more AI credits, or unlock faster workspaces.
Do I need to install Kotlin to use JDoodle?
No. JDoodle runs Kotlin on its servers. Open this page in a browser and execute.
Which Kotlin version should I pick on JDoodle?
Choose the version that matches the course or codebase you are working against from the version menu. The builds JDoodle has installed are 1.1.51 (JRE 9.0.1+11), 1.2.40 (JRE 10.0.1), 1.3.50 (JRE 11.0.4), 1.6.0 (JRE 17.0.1+12), 1.9.10 (JRE 17.0.1+12), and 2.3.10.
Can I add Maven libraries on JDoodle?
Yes, if the package is public. Private or local packages are not supported on this JDoodle page.
Can I run a multi-file Kotlin project online?
Not on this page, which runs a single Kotlin file. For several files in one project, open the JDoodle Kotlin IDE. Everything else works the same on both.
Is this an online Kotlin editor or a compiler?
Both. The page is an online Kotlin editor and it compiles and runs what you write.
Can I debug Kotlin code online?
Yes. JDoodle has a step debugger for Kotlin. Click a line number to set a breakpoint, press Debug, and the program stops there so you can step over, step into, and read the call stack. Local variables are listed with their values while you are paused, and you can open objects and arrays to look inside. Debugging runs on 2.3.10, the newest build here and the one this page opens with. Debugging is free, and a session runs for three minutes on the free plan or ten on a paid one.
Can I see a Kotlin GUI window online?
Yes. A Kotlin program that opens a window shows it here in the GUI tab, live, next to your Output. Tick GUI in the I/O row before you run, and the window appears as soon as your program draws one - you can click and type into it as you would on your own machine. The GUI window runs on 2.3.10, the newest build here and the one this page opens with. A window stays open for five minutes on the free plan or fifteen on a paid one, and every click or keystroke extends it.
Input, interactive runs, files, and the rest of the editor work the same on every language. See the JDoodle IDE documentation.