Welcome to Koin

The Pragmatic Kotlin Dependency Injection Framework - Simple AND Powerful

Koin is a lightweight dependency injection framework for Kotlin developers. Whether you're building Android apps, Kotlin Multiplatform projects, backend services with Ktor, or any Kotlin application, Koin makes dependency injection straightforward and intuitive.

Why Koin?

Koin was designed with a clear philosophy: you shouldn't have to choose between simplicity and capability. With Koin, you get both.

DSL & Annotations - Choose What You Want

Koin is powerful with both approaches. Prefer a clean Kotlin DSL? Use it. Like annotations? Use them. Both are first-class citizens, equally powerful.

Value	What it means
Productive	Easy to learn, easy to write. Get DI working in minutes, not hours
Developer-Friendly	DSL or Annotations - your choice. Clear errors, easy debugging, best DX
Scalable	Powers large enterprise applications with complex dependency graphs
Safe	Compile-time safety with Koin Compiler Plugin
Dynamic	Runtime flexibility: load modules dynamically, lazy loading, feature flags

Where to Start?

Choose your path based on your experience level:

New to Dependency Injection?

Start with the fundamentals:

• What is Dependency Injection? - Understand the core concepts

Know DI, New to Koin?

Jump right into Koin:

• What is Koin? - Discover Koin's approach to DI
• Koin Compiler Plugin - The recommended, safer way to use Koin

Coming from Hilt/Dagger?

See how Koin compares:

• Koin vs Hilt/Dagger - Understand the differences and migration path

Ready to Code?

• Setup Guide - Add Koin to your project
• Tutorials - Build your first Koin app

Koin's Approaches

Koin offers flexibility in how you define your dependencies:

Approach	Status	Description
Koin Compiler Plugin (Kotlin 2.x)	Recommended	DSL: single<MyService>(), factory<MyRepo>(), viewModel<MyVM>().
Koin Compiler Plugin (Kotlin 2.x)	Recommended	Annotations: @Singleton, @Factory, @KoinViewModel. Auto-detects dependencies, compile-time safety.
Classic DSL	Fully Supported	singleOf(::MyService), single { MyService(get()) }. Works with any Kotlin version. Compiler Plugin adds safety on top when you're ready.
KSP Annotations	Deprecated	Migrate to Compiler Plugin - same annotations, better processing.

Learn more in What is Koin? and Koin Compiler Plugin.

Platform Support

Koin works everywhere Kotlin runs:

Platform	Package	Status
Kotlin/JVM	koin-core	✅ Full support
Android	koin-android	✅ Full support
Compose (Multiplatform)	koin-compose	✅ Full support
iOS	koin-core	✅ Full support
Desktop	koin-core	✅ Full support
Web (JS/Wasm)	koin-core	✅ Full support
Ktor	koin-ktor	✅ Full support

Quick Example

Here's a taste of what Koin looks like:

// Define your classes
class UserRepository(private val api: ApiService)
class UserViewModel(private val repository: UserRepository) : ViewModel()

// Define your module with Compiler Plugin DSL
val appModule = module {
    single<ApiService>()
    single<UserRepository>()
    viewModel<UserViewModel>()
}

// Start Koin
startKoin {
    modules(appModule)
}

// Inject in your Activity
class MainActivity : AppCompatActivity() {
    private val viewModel: UserViewModel by viewModel()
}

Or with annotations:

@Singleton
class UserRepository(private val api: ApiService)

@KoinViewModel
class UserViewModel(private val repository: UserRepository) : ViewModel()

@Module
@ComponentScan("com.myapp")
class AppModule

Ready to get started? Head to the Setup Guide.