Try Kotlin in Your Browser: New Look and More Features

Andrey Breslav

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.


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

  1. Даниил Водопьян says:

    April 16, 2015

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

  2. B7W says:

    April 16, 2015

    UI is too boring, add more colours!

  3. Neil says:

    April 17, 2015


    How about allowing login using our accounts?

  4. Даниил Водопьян says:

    April 17, 2015

    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

    • Andrey Breslav says:

      April 17, 2015

      No, we won’t. Inline code snippets are more convenient and don’t have to compile at all.

  5. QuangSon says:

    April 17, 2015

    I love it.

    Hope kotlin will be release version 1.0 NOW 🙂

    • Даниил Водопьян says:

      April 17, 2015

      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:

        April 18, 2015

        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:

    April 18, 2015

    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:

    April 27, 2015

    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,

    • Andrey Breslav says:

      April 28, 2015

      I’m glad to hear that you are considering Kotlin now. Thanks

  8. lazyval says:

    May 14, 2015

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