Try Kotlin in Your Browser: New Look and More Features

We released Kotlin Web Demo quite a while ago, it did a good job helping people try Kotlin right in the browser and share runnable code with each other. Now, a shiny new version is ready, it’s time to retire the old one.

Meet, as new incarnation of a web-based mini-IDE for Kotlin.


The new version brings

  • Shiny new design
  • Full-screen mode
  • JUnit support (including a smart Test Results view)
  • Multi-file projects (some files in our examples, such as tests, are read-only)
  • Navigation from stack traces to code

Sharing Your Code

You can log in with your Google, Facebook or Twitter accounts. When logged in, you can create new projects and copy example projects to change them.

Any saved project (our example or your custom code) can be shared by simply copy-and-pasting the link from the address bar.

For example, here’s a link to an example program.
And this is the link to my code about expressing Go’s defer as a Kotlin library.

Old Web Demo

The old Web Demo is retired, and put into a read-only mode for the time being. You can still run your programs, but can not modify them or create new ones.

All accounts and programs created for Kotlin Web Demo have been migrated to


Your feedback is welcome, as usual.


About Andrey Breslav

Andrey is the lead language designer of Kotlin at JetBrains.
This entry was posted in Tools. Bookmark the permalink.

16 Responses to Try Kotlin in Your Browser: New Look and More Features

  1. Даниил Водопьян says:

    Very cool ! Auto typecheck is something huge! (BTH make the check box more visible)
    Would you bother to put Koans there?

  2. B7W says:

    UI is too boring, add more colours!

  3. Neil says:


    How about allowing login using our accounts?

  4. Даниил Водопьян says:

    Please add a way to insert links to the web-demo from kotlin blog comments.
    After that, please advertise to do that, so we would not see bad-formated-plain-text-code-comments any more

  5. QuangSon says:

    I love it.

    Hope kotlin will be release version 1.0 NOW :)

    • Даниил Водопьян says:

      Ha, do you really think that’s possible? After all the resent changes in the design Kotlin needs at least 6 mouths just to test them 😀

      • QuangSon says:

        Thanks for share :)

        I actual love Kotlin.
        Kotlin for android is great.
        I will use it, Hope Kotlin will release in this year.

  6. Damian Petla says:

    It’s a great improvement. In the future we will write Android apps programming in Kotlin on the web and running with Chrome extensions. That would be awesome!

  7. Yuri Ushakov says:

    Hey Andrey,

    I’m seriously using Scala for the first time for the last six months and just wanted to say I’ve been a big sceptic of Kotlin. Now that I’m getting huge problems debugging a Spray application which is full of implicits I’m thinking thank god this app is a prototype, and maybe I should do the big one in Kotlin after all.

    Best regards,

  8. lazyval says:

    Is there any backing [github] repo for this nifty thing?

Comments are closed.