MobileBackendTable-stakesAround since 2011
Kotlin
Google's preferred programming language for Android development — the modern standard, having largely replaced the older Java for new Android work.
Think of it like
Like the current-model tool from Google's own toolkit, replacing an older tool (Java) most new work has moved on from.
Junior or senior?
Junior sounds like
Has only used Kotlin for Android.
Senior sounds like
Can say whether they've also used it on the backend, outside of mobile.
Ask them
“Is your Kotlin experience purely Android, or have you also used it on the backend?”