Kotlin

Kotlin is the language most new Android apps are written in, and that is not just fashion. Google recommends it, and the free tools Google publishes for Android are built around it, so the easy path leads there. If someone is writing an app for Android phones this year, Kotlin is very likely what is on their screen.

It did not arrive as a clean break, which is a large part of why it won. Kotlin runs on the same foundation as Java, the language Android used for its first ten years, and it can still call every existing Java library. So a team with an old Java app converts one file, ships it, and converts the next one a month later, without anything stopping. That is unusual, because most language changes mean a full rewrite, and a rewrite means months where the customer sees nothing new and keeps paying.

What Kotlin takes away is typing, and one particular crash. A large share of the crashes people actually saw in older Android apps came from a single mistake: the app asked for something that was not there. It might be a phone number the customer never filled in, or a photo that failed to download. Kotlin builds that difference into the language, so a value that might be missing must be marked as possibly missing, and the compiler refuses code that ignores the mark. The crash is not fixed later; it never gets written.

The same screen often ends up half the length it was in Java, and shorter code is cheaper to read and change a year later. That second year is where most of an app's budget goes, not the first build, and it is what people underestimate. Linkysoft prices mobile app work with that in mind, because the app you launch is never the app you keep.

One thing needs to be clear, because suppliers blur it: Kotlin does not make your app run on an iPhone. There is a version that shares the rules underneath, such as prices, stock counts and opening hours, between an Android app and an iPhone one. Each phone still gets its own screens, so ask exactly what is shared before you accept the words cross-platform. Kotlin also runs on servers, so one team can write the app and the web application behind it. That is how the Android stock app in Storek reads the same numbers as the counter, and why Linkysoft normally puts one team on both sides.