Deep understanding of Flutter's Architecture: 0 — Introduction

Introduction to a series of articles about flutter's architecture, working and it's understanding

Hi, I am Pardeep Kumar, a software engineer and Flutter enthusiast from India. I have been following the Flutter journey since its version of 1.2.1 but realized that I have not contributed to the Flutter community, yet. So I am more than intrigued to introduce a new article series — Flutter Architecture. In the series, I will do my best to describe flutter's architecture.

Table of Contents

• About the series
• Minimalist overview flutter architecture
• How Flutter’s Architecture Delivers a Beautiful Application
• Other articles in this series
• Your contribution

About the series

In each article of the series, we’ll cover important aspects of Flutter architecture and breaking them down into 7 easy-to-understand sections, so you can expect more than 7 articles in the series! I will do my best to be consistent and publish a new article to the series weekly.

What is Flutter Architecture?

Flutter’s architecture is central to transforming a single codebase into a seamless, beautiful application across multiple platforms. It does this by leveraging its layered design, from high-level widgets down to the rendering engine and platform-specific integrations. Flutter apps are compiled directly to machine code, whether Intel x64 or ARM instructions, or to JavaScript if targeting the web. Here’s a breakdown of how each component in Flutter’s architecture contributes to building polished, performant apps.

Widget-Based Framework: Building Blocks of UI

Flutter’s widget-centric approach is the foundation of its architecture. Widgets represent everything from structural elements like buttons and text to complex layouts and animations. By composing UI elements from reusable widgets, developers can create a consistent, beautiful design that responds dynamically to user interactions. This widget layer is highly customizable, which allows for unique, brand-specific designs while maintaining UI consistency.

Rendering Engine: Direct Control Over Every Pixel

Flutter uses the Impeller on iOS and coming to Android and macOS, and Skia on other platforms (The Heart of Rendering), which renders each pixel directly on the screen, bypassing the need for platform-specific UI components. This architecture enables Flutter to achieve native-like performance and consistency in design across platforms, allowing for a high degree of customization without sacrificing speed. The engine’s independence from Original Equipment Manufacturer (OEM) widgets means Flutter apps look and feel the same on both Android and iOS, giving users a unified experience.

Dart Runtime: Fast and Flexible Code Execution

Flutter uses the Dart language, which supports both ahead-of-time (AOT) and just-in-time (JIT) compilation. JIT enables fast development iterations with Flutter’s hot reload, while AOT compilation ensures high performance for release builds. This combination allows developers to see real-time changes during development, significantly speeding up the design and testing process, ultimately helping to fine-tune the app’s visual appeal.

Platform Channels: Access to Native Functionality

Through platform channels, Flutter can seamlessly integrate with native code (Swift, Kotlin, Java, Objective-C) on both Android and iOS. This layer ensures that Flutter apps can access device-specific functionalities—like the camera, GPS, and storage—while still maintaining a consistent look and feel across different devices. This access makes Flutter an excellent choice for applications that need native functionality without sacrificing visual consistency.

Material and Cupertino Libraries: Native Design Language Support

Flutter provides out-of-the-box support for Material Design (Android) and Cupertino (iOS) styles, allowing apps to look native on their respective platforms. This architectural choice ensures a familiar user experience, making it easy to adopt design patterns native to each platform without separate codebases. This blend of platform-specific and custom design flexibility helps deliver a visually cohesive app experience.

How Flutter’s Architecture Delivers a Beautiful Application

Each part of Flutter’s architecture—widget-based design, direct pixel rendering, a fast runtime, and platform-specific integration—works together to produce a highly customizable, performant, and visually consistent app. By handling everything from layout and styling to animation, Flutter’s layered architecture empowers developers to build beautiful applications that are reliable, responsive, and ready for users on multiple platforms.

The Build Process: From Code to Application

When you’re ready to release your app, the Flutter build process takes over. Here’s what happens:

1. Compilation: Your Dart code is compiled into either JIT (Just In Time) for debugging or AOT (Ahead Of Time) for release.
2. Asset Bundling: All resources and assets, such as images and fonts, are bundled into the app package.
3. Native Packaging: The AOT compiled app and the bundled assets are packaged into a native container, such as an APK for Android or an IPA for iOS.
4. Signing: The package is signed with a developer certificate, which is necessary for distributing the app on platforms like the Google Play Store or Apple App Store.

With these processes, your Flutter app is transformed into an executable package that can run smoothly on your target platform

I hope this article encouraged you to learn more about Flutter’s architecture. New articles are on their way so stay tuned and happy coding!

Other articles in this series

• 0 - Introduction
• 1 - Layer Model
• 2 - Reactive User Interfaces
• 3 - Introduction to Widgets
• 4 - Rendering Process
• 5 - Platform Embedders
• 6 - Integrating Flutter with Other Code
• 7 - Support for the Web

Your contribution

?? Leave a response to this article by providing your insights, comments or wishes for the series.