Progress · 0/6 phases

🌐 🌐 Kotlin Multiplatform (KMP) — Complete Roadmap

4 min read · Notion

🌐 One Kotlin codebase. Android. iOS. Desktop. Web. From KMP project setup to production-grade shared logic, Compose Multiplatform UI, iOS interop with SKIE, and full CI/CD pipeline.

📌 What this roadmap covers

KMP is not “write once run anywhere.” It is share logic, own the platform. Business rules, networking, databases, and state management live in shared Kotlin. The UI and platform-specific behaviour stay native or use Compose Multiplatform. This roadmap builds that system end-to-end.

🗺️ Roadmap at a glance

Phase	Days	Focus	Key Output
Phase 1 — KMP Foundations	Days 1–12	Project structure, source sets, expect/actual, Gradle KSP	Working KMP project on Android + iOS
Phase 2 — Shared Business Logic	Days 13–28	Ktor, SQLDelight, Koin, kotlinx.serialization, coroutines	Full shared data layer
Phase 3 — Compose Multiplatform	Days 29–42	CMP UI, Voyager navigation, shared design system, animations	Identical UI on Android + iOS + Desktop
Phase 4 — Platform APIs & iOS Interop	Days 43–54	SKIE, Swift interop, camera, GPS, Keychain, notifications	Native platform features from shared Kotlin
Phase 5 — Production & CI/CD	Days 55–60	Testing, Fastlane, GitHub Actions, App Store + Play Store	Fully automated ship pipeline

🛠️ Complete tech stack

Layer	Technology
Language	Kotlin 2.x
Build	Gradle Kotlin DSL + Convention Plugins
Shared UI	Compose Multiplatform (CMP)
Navigation	Voyager
Networking	Ktor Client
Local DB	SQLDelight
DI	Koin
Serialisation	kotlinx.serialization
Async	Kotlin Coroutines + Flow
iOS Interop	SKIE
Image loading	Coil 3 (KMP)
Date/Time	kotlinx-datetime
Testing	kotlin.test, Turbine, Paparazzi
CI/CD	GitHub Actions + Fastlane
Analytics	Firebase KMP wrapper

📁 Full project structure

MyKMPApp/
├── build-logic/                    # Convention plugins
│   └── src/main/kotlin/
│       ├── KmpLibraryConventionPlugin.kt
│       └── AndroidAppConventionPlugin.kt
├── shared/                         # Shared KMP module
│   └── src/
│       ├── commonMain/kotlin/
│       │   ├── data/
│       │   ├── domain/
│       │   └── presentation/
│       ├── commonTest/kotlin/
│       ├── androidMain/kotlin/
│       ├── androidTest/kotlin/
│       ├── iosMain/kotlin/
│       └── iosTest/kotlin/
├── composeApp/                     # Compose Multiplatform UI
│   └── src/
│       ├── commonMain/kotlin/          # All Compose UI here
│       ├── androidMain/kotlin/         # Android entry point
│       ├── iosMain/kotlin/             # iOS entry point
│       └── desktopMain/kotlin/         # Desktop entry point
├── androidApp/                     # Android standalone (optional)
├── iosApp/                         # Xcode project
│   ├── iosApp.xcodeproj/
│   └── iosApp/
│       └── ContentView.swift
└── gradle/
    └── libs.versions.toml              # Version catalog

📊 My progress

Current phase: Phase 1
Current day: Day 1 of 60
Platforms running: 0 / 4
Shared modules built: 0
KMP apps shipped: 0

🔖 Phase pages

📦 Phase 1 — KMP Foundations (Days 1–12)
📁 Phase 2 — Shared Business Logic (Days 13–28)
🎨 Phase 3 — Compose Multiplatform UI (Days 29–42)
📱 Phase 4 — Platform APIs & iOS Interop (Days 43–54)
🚀 Phase 5 — Production & CI/CD (Days 55–60)

📘 The KMP mental model

commonMain        — pure Kotlin. NO platform imports. Runs on every target.
                    Domain models, use cases, repository interfaces,
                    Ktor calls, SQLDelight queries, Koin modules, Flows.
 
androidMain       — Android-specific actual implementations.
                    Context, Android Keystore, Room (if not using SQLDelight).
 
iosMain           — iOS-specific actual implementations.
                    UIKit/SwiftUI interop, Keychain, NSUserDefaults.
 
desktopMain       — JVM desktop implementations.
                    File system, system tray, JVM-specific APIs.

The rule: if you find yourself importing android.* or platform.UIKit.* inside commonMain/, you need an expect/actual abstraction.

📅 KMP Daily Tracker