KMP vs Flutter
Both Kotlin Multiplatform (KMP) and Flutter help you build cross-platform apps, but they work in very different ways.
1. What They Are
✨ Kotlin Multiplatform (KMP)
A shared-logic cross-platform framework by JetBrains / Kotlin team.
UI is NOT shared (mostly).
You share:
Business logic
- Network calls
- Database logic
- ViewModels
- Utils
- UI is written natively (Android Compose, SwiftUI, etc.)
Where KMP runs?
- ✔ Android
- ✔ iOS
- ✔ Desktop
- ✔ Web
- ✔ Backend
- ✔ Compose Multiplatform UI (optional shared UI)
✨ Flutter
- A full UI + logic cross-platform framework by Google.
- Uses Dart language.
- Renders everything using Flutter’s own UI engine.
- UI and logic are fully shared across platforms.
Where Flutter runs?
✔ Android
✔ iOS
✔ Web
✔ Desktop
✔ Embedded devices
2. Architecture Difference
Key Differences Table
KMP Architecture
| Feature | KMP (Kotlin Multiplatform) | Flutter |
|---|---|---|
| Language | Kotlin | Dart |
| UI | Native UI (Compose, SwiftUI) or Compose Multiplatform | Flutter UI (fully custom) |
| Code Sharing | Logic only (mostly) | 100% UI + Logic |
| Performance | Native-level | Near-native (Skia engine) |
| Learning Curve | Easy for Android devs | Medium (learn Dart + Flutter widgets) |
| App Size | Smaller | Bigger (engine included) |
| Community | Growing fast | Very large |
| Ideal For | Apps needing native UI | Fast cross-platform UI-heavy apps |
| Access to Platform APIs | Direct (native bindings) | Via channels (slower) |
3. When to Choose What
Choose KMP if:
- You are an Android developer (Kotlin experience).
- You want native UI on iOS.
- You need native performance.
- You want one shared logic across Android, iOS, Desktop, and Web.
- You want a long-term, officially backed Kotlin ecosystem.
Choose Flutter if:
- You want one UI for all platforms.
- You want fast development (Hot Reload).
- You want consistent design on Android + iOS + Web.
- You want to build a UI-heavy or animation-heavy app.
- Your team does not want to write platform-specific UIs.
4. Performance Comparison
| Task | KMP | Flutter |
|---|---|---|
| UI Rendering | Native speed | Very fast but not native |
| Heavy computation | Native Kotlin | Runs in Dart VM / JIT / AOT |
| Smooth animations | Depends on native UI | Extremely smooth (Skia) |
| Startup time | Faster | Slightly slower |
5. Real-World Use Cases
Companies using KMP
- Netflix
- Philips
- Baidu
- CashApp (Square)
Companies using Flutter
- BMW
- Alibaba
- Dream11
- ByteDance (TikTok)
6. Final Verdict
If you want native feel → Choose KMP
Best for long-term, scalable apps where each platform needs its own UI but logic is shared.
If you want same UI everywhere → Choose Flutter
Best for startups, MVPs, dashboards, and UI-heavy apps.
Section 1 — Multiple Choice Questions (MCQs)
1. Kotlin Multiplatform primarily focuses on sharing:
a) UI only
b) Business logic only
c) UI + Business logic
d) Network + UI
2. Flutter uses which programming language?
a) Kotlin
b) Dart
c) Java
d) Swift
3. KMP apps use which UI framework on iOS?
a) SwiftUI
b) Jetpack Compose
c) Flutter Widgets
d) React Native
4. Flutter UI is:
a) 100% platform-native
b) Partially shared
c) Fully shared across all platforms
d) Not shared
5. KMP enables code sharing across:
a) Only Android and iOS
b) Mobile + Desktop + Web
c) Only mobile apps
d) Web only
6. Flutter renders UI using:
a) Native UI controls
b) Skia rendering engine
c) HTML DOM
d) WebView
7. Which is better for animation-heavy apps?
a) KMP
b) Flutter
c) Both
d) None
8. KMP apps on Android typically use:
a) Jetpack Compose
b) UIKit
c) HTML5
d) Skia
Section 2 — Fill in the Blanks
- Flutter provides a ______ UI framework shared across all platforms.
- KMP is mainly used to share ______ and business logic.
- Flutter apps use ______ language.
- KMP is developed by ______.
- Flutter is developed by ______.
- KMP can use Compose Multiplatform for ______ UI.
- Flutter uses the ______ engine for rendering.
Section 3 — True or False
- KMP allows you to write one UI for all platforms.
- Flutter UI is fully custom and not platform-native.
- KMP is ideal for native performance.
- Flutter requires writing separate UI for Android and iOS.
- KMP uses SwiftUI for building iOS views.
- Flutter has a hot reload feature.
Section 4 — Short Answer Questions
- What is Kotlin Multiplatform (KMP)?
- What are the primary platforms supported by Flutter?
- Explain why KMP is good for native performance.
- Why does Flutter provide a consistent UI across devices?
- Name two companies using KMP.
- Name two companies using Flutter.
- What type of tasks benefit most from KMP?
- What type of apps benefit most from Flutter?
Section 5 — Long Answer / Explanation Questions
- Compare the architecture of KMP and Flutter.
- Explain the advantages and disadvantages of using KMP in a real-world project.
- Explain the advantages and disadvantages of Flutter in mobile development.
- Write a detailed comparison of UI rendering between KMP and Flutter.
- Discuss which framework is more suitable for a startup building an MVP and why.
Section 6 — Match the Following
| Column A | Column B |
|---|---|
| 1. Flutter | b. Dart |
| 2. KMP iOS UI | a. SwiftUI |
| 3. Flutter language | b. Dart |
| 4. Shared UI in KMP | c. Compose Multiplatform (optional) |
| 5. KMP Android UI | e. Jetpack Compose |
Section 7 — Case Study Questions
1. Startup Project
A startup wants to create an app with the same UI for Android, iOS, Web, and Desktop.
Which framework should they choose and why?
2. Enterprise Project
A banking company wants a native feel on Android and iOS but wants to share authentication, database, and API logic.
- Is Flutter suitable?
- Is KMP suitable? Explain your reasoning.
3. Fast UI Development
A team wants fast development, animations, and hot reload.
Which framework fits this scenario?
Section 8 — Coding-Based Questions
1. Write a sample shared KMP function.
Example:
A function to calculate user score.
2. Write a simple Flutter Widget.
Example:
A button with a click counter.
Section 1 — MCQs (Answers)
1. (b) Business logic only
2. (b) Dart
3. (a) SwiftUI
4. (c) Fully shared across all platforms
5. (b) Mobile + Desktop + Web
6. (b) Skia rendering engine
7. (b) Flutter
8. (a) Jetpack Compose
Section 2 — Fill in the Blanks (Answers)
1. custom
2. shared logic
3. Dart
4. JetBrains
5. Google
6. shared
7. Skia
Section 3 — True or False (Answers)
- False
- True
- True
- False
- True
- True
Section 4 — Short Answer Questions (Sample Answers)
- Kotlin Multiplatform is a framework that allows sharing business logic across platforms while keeping UI native.
- Flutter supports Android, iOS, Web, Desktop, and embedded devices.
- KMP uses native UI frameworks and runs Kotlin code natively, so performance is near-native.
- Because Flutter uses one UI engine (Skia) to render the entire UI consistently across all platforms.
- Netflix, CashApp (Square)
- Google, BMW, Alibaba, Dream11
- Apps needing native UI, deep platform integration, and shared logic across multiple devices.
- UI-heavy apps, animation-heavy apps, or applications needing uniform UI on all platforms.
Section 5 — Long Answer Questions (Sample Key Points)
1. KMP vs Flutter Architecture
- KMP shares business logic; UI is native.
- Flutter shares UI + logic; uses custom rendering engine.
- KMP integrates with Android Studio + Xcode.
- Flutter uses Dart + Flutter SDK.
2. KMP Advantages & Disadvantages
Advantages:
- Native UI
- Strong Kotlin ecosystem
- Excellent performance
- Can share backend logic
Disadvantages:
- UI not shared (unless using Compose Multiplatform)
- Slower to build UI-heavy apps
- Smaller community
3. Flutter Advantages & Disadvantages
Advantages:
- One UI for all platforms
- Fast development (Hot Reload)
- Smooth animations
- Large community
Disadvantages:
- Not native UI
- Larger app size
- Needs platform channels for native APIs
4. UI Rendering Comparison
- KMP uses native components (Compose, SwiftUI).
- Flutter uses Skia engine to draw everything.
- KMP follows platform design automatically.
- Flutter offers identical UI everywhere.
5. Which is better for MVP?
- Flutter: single UI, fast build, great for startups.
- KMP suitable only if project needs native UI from day one.
Section 6 — Match the Following (Answers)
Column A Answer
1. Flutter b. Dart
2. KMP iOS UI a. SwiftUI
3. Flutter language b. Dart
4. Shared UI in KMP c. Compose Multiplatform (optional)
5. KMP Android UIe. Jetpack Compose
Section 7 — Case Study Answers
1. Startup Project
Flutter, because it provides one shared UI + logic for Android, iOS, Web, Desktop → fastest development.
2. Enterprise Project
- Flutter is NOT ideal because they want native UI.
- KMP is ideal because it allows shared logic + native UI for both Android and iOS.
3. Fast UI Development
Flutter, because it has hot reload and excellent animation performance.
Section 8 — Coding Questions (Sample Answers)
1. KMP Shared Function
fun calculateScore(a: Int, b: Int): Int {
return a + b
}2. Flutter Button Widget
import 'package:flutter/material.dart';
class CounterButton extends StatefulWidget {
@override
_CounterButtonState createState() => _CounterButtonState();
}
class _CounterButtonState extends State {
int count = 0;
@override
Widget build(BuildContext context) {
return ElevatedButton(
onPressed: () {
setState(() {
count++;
});
},
child: Text("Count: $count"),
);
}
}
