Kotlin

Statically typed programming language that runs on the JVM, compiles to JavaScript and native binaries, and interoperates with Java at the bytecode level. Combines concise syntax with null safety, coroutines for structured concurrency, and multiplatform support, allowing shared code across Android, iOS, server, and web from a single codebase.

Developed by JetBrains and backed by the Kotlin Foundation. Adopted by McDonald's, AWS, Philips, Adobe, Forbes, and Atlassian for Android apps, server-side services, and cross-platform mobile. Chosen over Java for its expressiveness, reduced boilerplate, and safer concurrency model. Kotlin Multiplatform lets teams share business logic while keeping native UI per platform.

Key capabilities:

• Full Java interop: call Java from Kotlin and Kotlin from Java without adapters
• Coroutines and structured concurrency for async flows without callbacks
• Kotlin Multiplatform to share code across Android, iOS, macOS, Windows, Linux, and the web
• Null safety and smart casts baked into the type system
• First-class functions, data classes, and sealed hierarchies for cleaner APIs

Teams use Kotlin for Android apps as the recommended language, backend services on Spring Boot or Ktor, and shared logic across mobile platforms with KMP. Integrates with Gradle, Maven, and IDEs including IntelliJ IDEA and VS Code.