You might think that Kotlin is the programming language of Android… Well, it's only partially true, and that's not even Kotlin's raison d'être. Kotlin 1.0 (2016) had experimental support for JavaScript, and 6 years later, we're sticking to it on the WEB, in the backend, on Android of course, and now on (native) iOS as well! Come to learn why you might, or might not want to follow suit. This talk will be both an up to date introduction to Kotlin, and sharing our experience with it on the WEB.