Technology
Kotlin
Kotlin is for a Play build that has to last. We use it when a wrapper is not honest, and we still share the API with the web.
What it is
Kotlin is JetBrains' language, and Google's preferred language for Android. It runs on the JVM, so it also shows up in back ends (Ktor, Spring) and in multiplatform projects that share logic between Android and iOS. It is Java with the sharp edges filed down, and a type system people actually want to use.
On Android it is the default for new modules. Coroutines, Jetpack Compose, and the Play toolchain assume you can read Kotlin. A team still writing only Java is not wrong, but they are swimming upstream.
What it does
Teams use Kotlin for Android apps first, then sometimes for shared mobile logic and for JVM services that want a modern language without leaving the Java ecosystem. Compose is the UI layer Google is pushing. Views remain in a lot of production apps.
We write Kotlin when Android is in the brief. We share the API with the site. We do not invent a second domain model for the phone.
Why we use it
Android in the language the platform expects.
Web first. Play later. Accounts already work. Dispatchers can stay in the browser while the field uses the phone. The Play Console is yours.
A wrapper is fine until it is not. We will say when Kotlin is the honest path.
Built on it
Android Jetpack, Play, and a large share of Google's own apps are Kotlin.
Netflix
The Android app is a flagship Kotlin codebase.
An early public Kotlin adopter on Android.
Slack
The Android client is Kotlin, next to a TypeScript desktop.
Gradle
The build tool's own language story includes Kotlin DSL as a first-class path.
Tell us what needs to ship.
You use a working prototype before the production build goes ahead.