Dependency Injection in Android: Hilt vs. Koin

💉 The DI Landscape

Dependency Injection (DI) is non-negotiable for scalable Android apps. But the battle between Hilt (Google’s official wrapper around Dagger) and Koin (Kotlin-first Service Locator) continues.

🏛️ Hilt (Dagger)

The giant. Built on compile-time code generation (KAPT / KSP).

Pros

• Compile-time safety: Fails fast if a dependency is missing.
• Performance: Zero reflection. Ideal for large apps.
• Integration: Deep support for Android components (Activity, Fragment, ViewModel, Compose).
• Testing: Makes swapping modules for tests straightforward.

Cons

• Build Time: Annotation processing slows down builds.
• Boilerplate: @Module, @InstallIn, @Provides.
• Complexity: Debugging generated Dagger code is a nightmare.

🦄 Koin

The pragmatic choice. Pure Kotlin. No code generation.

Pros

• Simplicity: Just a DSL. module { single { ... } }.
• Build Speed: No annotation processing.
• Kotlin Features: Reified types, DSLs.
• Multiplatform: Koin works seamlessly in KMP (iOS, Desktop).

Cons

• Runtime Safety: Crashes at runtime if dependency is missing (though verify() checks exist).
• Performance: Slight startup overhead due to graph resolution at runtime (negligible in modern devices).

🆚 Benchmark 2025

Feature	Hilt	Koin
Startup	Instant	Fast (~10ms)
Build Time	Slow	Fast
Learning Curve	High	Low
Safety	Compile-time	Runtime (mostly)
KMP Support	No (Dagger)	Yes (Native)

🚀 When to Choose What

Choose Hilt if:

• You are building a massive app with 100+ modules.
• You need absolute compile-time guarantees.
• You rely heavily on Google’s opinionated stack (Jetpack).

Choose Koin if:

• You are building a startup MVP or mid-sized app.
• You want fast iteration cycles.
• You are targeting Kotlin Multiplatform (KMP).

🏁 Conclusion

Both are excellent. In 2025, Koin’s simplicity and KMP support make it the winner for most new projects. Hilt remains the standard for legacy/large teams.