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Kotlin is a statically typed programming language developed by JetBrains.
It was designed to work particularly well with existing Java code while reducing some of the verbosity and common sources of errors found in traditional JVM development.
Kotlin can target several environments, including:
That gives teams the flexibility to use the same language across different parts of a software stack.
Kotlin code can also interoperate closely with Java, which makes it practical for companies with established JVM applications that want to introduce a newer language without rewriting everything.
Kotlin has grown from a popular Android language into a broader multiplatform programming ecosystem.
Kotlin can support several kinds of software development.
Android remains one of Kotlin's most important use cases.
Developers use Kotlin to build:
Modern Android applications frequently combine Kotlin with Jetpack Compose, Android Jetpack libraries, Room, Hilt, Retrofit, and coroutines.
Kotlin runs on the Java Virtual Machine, which allows it to use the huge existing JVM ecosystem.
Teams can build backend applications with frameworks such as:
Kotlin backend systems may handle:
Kotlin Multiplatform allows teams to share code across different platforms while retaining access to platform-specific capabilities.
A mobile product might share:
between Android and iOS.
The interface can still remain native where that provides the best product experience.
Compose Multiplatform allows teams to share declarative UI across supported platforms.
Depending on the product, teams can share interfaces across:
This goes beyond sharing only business logic.
Kotlin can be used for APIs, services, and business applications where teams want JVM infrastructure with more concise language features.
It can work particularly well in organizations already using Java libraries, databases, and cloud infrastructure.
Kotlin can support microservice architectures through frameworks such as Ktor and Spring Boot.
Services may handle:
Compose Multiplatform can support desktop applications written in Kotlin.
Companies may use it for:
Kotlin can target JavaScript and WebAssembly environments.
Kotlin/JS allows teams to compile Kotlin into JavaScript and interact with the broader JavaScript ecosystem.
Kotlin/Wasm expands the language into WebAssembly-based applications.
Companies can create reusable Kotlin modules shared between:
This can reduce duplicated business logic across products.
Kotlin can also be used for:
Strong Kotlin development requires understanding the language itself rather than relying entirely on Android or JVM frameworks.
Kotlin distinguishes between:
val for read-only referencesvar for mutable referencesUsing immutable values where practical can make application behavior easier to reason about.
Kotlin can infer many types automatically.
Developers don't need to declare every obvious type explicitly, which helps keep code concise while preserving static type checking.
Null safety is one of Kotlin's defining features.
Kotlin distinguishes between values that can and can't contain null.
For example:
String
represents a non-null string.
String?
represents a string that may also be null.
This allows many potential null-reference problems to be caught during development.
The safe-call operator allows developers to interact with nullable values without immediately forcing an unsafe assumption.
This can simplify common null-handling logic.
The Elvis operator allows developers to provide a fallback value when another value is null.
It's useful for:
Kotlin can often determine a more specific type after the code checks what a value contains.
This reduces repetitive manual casting.
Kotlin functions support capabilities such as:
This allows teams to create expressive APIs without excessive boilerplate.
Functions can receive other functions as arguments or return functions.
This appears frequently in:
Lambdas provide concise anonymous functions.
They're common throughout Kotlin and Android libraries.
Kotlin supports object-oriented programming through classes and objects.
Developers should understand:
Data classes provide a concise way to represent information-focused objects.
They automatically provide useful functionality for values such as:
They're commonly used for:
Sealed hierarchies allow developers to represent a restricted set of possible types.
They're useful for modeling application states such as:
or domain workflows such as:
The compiler can help ensure each possibility is handled.
Enums are useful when a value belongs to a fixed set of simple options.
Examples include:
Interfaces define contracts that multiple implementations can satisfy.
They can support:
Abstract classes can provide shared implementation while requiring subclasses to define certain behaviors.
Extension functions allow developers to add useful functions to an existing type without modifying the original class.
This is one of Kotlin's most recognizable language features.
Used carefully, extensions can make APIs more expressive.
Generics allow reusable functions and classes to work safely across different data types.
They're useful for:
Generics can also specify requirements for the types they accept.
This allows teams to create flexible APIs without losing meaningful guarantees.
Kotlin includes strong APIs around:
It also distinguishes between read-only and mutable collection interfaces.
Developers frequently transform collections using functions such as:
These capabilities make data-processing code concise and expressive.
Kotlin includes functions such as:
letrunwithapplyalsoThey can simplify object configuration and transformations when used intentionally.
Overusing scope functions can also make code difficult to follow, so developers should understand the differences between them.
Kotlin provides language-level support for delegation.
Developers can delegate interface implementation or property behavior instead of relying on deeper inheritance hierarchies.
Kotlin properties can include custom getters and setters.
This provides a cleaner abstraction than exposing raw fields.
The lazy delegate can delay creating a value until it is first needed.
lateinit allows selected non-null properties to be initialized after object construction.
Developers should understand where this is useful and when it creates unnecessary runtime assumptions.
Kotlin can create singleton objects directly through the language.
Companion objects can also associate functionality with a class.
Kotlin supports exceptions for representing failure conditions.
Unlike Java, Kotlin doesn't require checked exceptions in function signatures.
One of Kotlin's biggest strengths is its ability to coexist with Java.
Kotlin can call Java libraries.
Java code can call Kotlin.
This allows teams to migrate existing applications incrementally.
Coroutines provide Kotlin's primary model for asynchronous and concurrent programming.
They allow code to suspend without blocking a thread.
Coroutines can be used for:
A suspend function can pause its execution and resume later without blocking the underlying thread.
Developers can use this model to write asynchronous code that looks closer to ordinary sequential code.
Coroutine scopes help define how long asynchronous work should live.
This is particularly important in applications where work needs to stop when a component or feature is no longer active.
Dispatchers influence where coroutine work executes.
Developers need to understand when work is:
rather than moving everything indiscriminately onto background threads.
Structured concurrency ties coroutine lifetimes to defined scopes.
This improves:
Flow represents asynchronous streams of values.
It can support:
Flows can be transformed through operators before being collected by a consumer.
StateFlow represents observable state that always has a current value.
It's frequently used in Android application architecture.
SharedFlow can broadcast values to multiple collectors.
It's useful for selected event or state-sharing patterns.
Channels provide another model for communicating values between coroutines.
Kotlinx Serialization allows teams to serialize and deserialize Kotlin objects.
It's commonly used with:
Inline functions can reduce the runtime overhead of some higher-order functions and enable advanced type-system features.
Reified generic types make type information available inside certain inline functions.
They can simplify APIs that otherwise require explicit class references.
Kotlin's syntax supports domain-specific language patterns.
Gradle Kotlin DSL and Jetpack Compose are examples of Kotlin's ability to create expressive configuration and UI APIs.
Kotlin sits within several different technology ecosystems.
Android is one of Kotlin's largest development environments.
Modern Android development may involve:
Jetpack Compose is Android's modern declarative UI toolkit.
Developers use Kotlin functions to define interface components instead of relying entirely on traditional XML layouts.
Kotlin Multiplatform allows teams to share code across different targets.
That can include:
Compose Multiplatform extends the Compose programming model beyond Android and allows supported UI code to be shared across multiple platforms.
Java and Kotlin work closely together on the JVM.
Kotlin can use existing Java libraries and frameworks, making migration relatively straightforward.
Spring Boot supports Kotlin and can be used to create:
Ktor is a Kotlin-oriented framework for creating asynchronous server and client applications.
It can support:
Micronaut supports Kotlin alongside Java and other JVM languages for backend and microservice development.
Gradle is widely used to build Kotlin projects.
Teams may use Kotlin DSL for strongly typed build configuration.
IntelliJ IDEA provides deep Kotlin language support and is commonly used for JVM, backend, and multiplatform development.
Android Studio provides the main development environment for native Android applications.
Retrofit is commonly used in Android applications to communicate with HTTP APIs.
Room provides a database abstraction for local Android persistence.
Dependency-injection tools such as Hilt and Dagger appear frequently in Android architectures.
The coroutines library provides Kotlin's widely used concurrency capabilities, including Flow.
Kotlinx Serialization provides multiplatform serialization support.
SQLDelight can generate type-safe Kotlin APIs from SQL and is particularly relevant to multiplatform applications.
A modern Android application might look like this:
Kotlin becomes the language connecting UI, state, concurrency, networking, persistence, testing, and the wider Android ecosystem.
A Kotlin Multiplatform application may use a shared module containing:
Android and iOS applications can consume that shared code.
Teams can then choose between two broad approaches.
They can share logic while keeping SwiftUI and Jetpack Compose interfaces native.
Or they can use Compose Multiplatform to share more of the UI as well.
Multiplatform doesn't automatically mean sharing every line of code. Strong architecture identifies which functionality benefits from sharing and which behavior should remain platform-specific.
Kotlin appears across several software-development roles.
A Kotlin Developer specializes in applications where Kotlin is a primary programming language.
They may work across Android, JVM, backend, or multiplatform development.
An Android Developer specializes specifically in Android applications.
Most modern Android roles involve substantial Kotlin expertise.
A Mobile Developer may use Kotlin alongside Swift, Flutter, React Native, or another mobile-development technology.
A Kotlin Multiplatform Developer specializes in sharing application logic or interfaces across platforms using Kotlin Multiplatform.
A Back-End Developer may use Kotlin with Spring Boot, Ktor, or another JVM framework.
A Java Developer working in a mixed JVM environment may also contribute to Kotlin modules.
A Full-Stack Developer in a JVM organization may use Kotlin on the backend while working with another technology for the web interface.
Kotlin is the programming language.
Android Development is the broader discipline of building applications for Android devices.
Android development can include:
A developer can know Kotlin without being an Android specialist.
For example, someone may use Kotlin primarily for Spring Boot backend systems.
Kotlin and Java both run extensively on the JVM.
Kotlin adds language features such as:
Java has an enormous existing ecosystem and remains heavily used across business applications, Android legacy codebases, and backend systems.
Their interoperability means many companies use both.
Kotlin and Swift are both modern statically typed languages closely associated with mobile development.
Kotlin is widely used across Android and JVM environments.
Swift is central to Apple's software ecosystem.
Companies building fully native mobile products may use:
Kotlin → Android
Swift → iOS
Kotlin Multiplatform can also allow teams to share selected code between the two platforms.
Kotlin is a programming language with native Android, JVM, and multiplatform capabilities.
Flutter is a cross-platform UI framework using Dart.
Kotlin Multiplatform can preserve more direct access to native platform development while allowing teams to share selected code.
Flutter generally approaches cross-platform development through one UI framework across platforms.
The better choice depends on:
Kotlin is a statically typed programming language developed by JetBrains.
It can target the JVM, Android, native platforms, JavaScript, WebAssembly, and multiplatform applications.
No.
Android is one of its most important use cases, but Kotlin is also used for JVM backend development, Kotlin Multiplatform, server software, desktop applications, web projects, and reusable libraries.
Important skills include null safety, functions, classes, data classes, sealed types, extension functions, generics, collections, coroutines, Flow, Java interoperability, testing, and Gradle.
Coroutines provide a structured way to perform asynchronous and concurrent work without blocking threads unnecessarily.
They're widely used for networking, database access, background tasks, and event-driven application state.
Flow represents an asynchronous stream of multiple values over time.
It's commonly used for state, database changes, events, and reactive data pipelines.
Kotlin Multiplatform allows teams to share Kotlin code across different platforms while retaining the ability to use platform-specific functionality where required.
Yes.
Kotlin Multiplatform can share business logic, networking, models, persistence, and other functionality between Android and iOS applications.
Yes.
Kotlin works with JVM frameworks such as Spring Boot and Kotlin-oriented frameworks such as Ktor.
Yes.
Kotlin was designed for strong Java interoperability and can use existing Java classes and libraries.
Kotlin Developers, Android Developers, Mobile Developers, Kotlin Multiplatform Developers, Back-End Developers, and some Java Developers use Kotlin.
Understanding Kotlin helps you identify whether your product needs stronger Android development, JVM backend engineering, coroutines, multiplatform architecture, or shared mobile functionality.
If you need someone dedicated to building production software with the language, South can help you hire Kotlin Developers in Latin America.
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