Flutter is a layered system comprising the framework, the engine, and platform-specific embedders. Flutter applications are built using Google’s Dart object-oriented programming language. The Flutter engine itself is written primarily in C/C++. And the Skia library is the backbone of Flutter’s graphics capabilities.

Dart is the foundation for many of Flutter’s performance advantages. It supports both ahead-of-time (AOT) and just-in-time (JIT) compilation. AOT compiled code into lower-level native code, which leads to apps that startup faster and have higher performance. JIT facilitates Flutter’s hot reload capability (discussed in greater detail below), which reduces development time. Dart also compiles directly to native ARM or Intel x64 code, minimizing performance differences between Flutter apps, and native applications that rely on intermediate code interpretations at runtime.

Flutter’s architecture also makes it simple and quick to add functionality or accommodate new users, and, as a result, it is highly extensible and scalable.