Xamarin is a Microsoft-owned, open-source framework for building cross-platform mobile applications using C# and the .NET ecosystem. It enables developers to write a single codebase that runs natively on both iOS and Android, sharing up to 90% or more of the application logic while still delivering platform-specific user interfaces and performance characteristics that match native development.
Xamarin achieves native performance through two primary approaches. Xamarin.iOS uses ahead-of-time (AOT) compilation to produce native ARM code, while Xamarin.Android uses just-in-time (JIT) compilation on the device. Both platforms provide direct access to the full range of native APIs, meaning developers can leverage platform-specific features like camera access, GPS, push notifications, and biometric authentication without sacrificing functionality.
The Xamarin ecosystem offers several development models:
- Xamarin.Native for platform-specific UI with shared business logic
- Xamarin.Forms (now .NET MAUI) for shared UI code across platforms
- Full Visual Studio integration with debugging, profiling, and testing tools
- NuGet package manager access to the vast .NET library ecosystem
While Xamarin was a pioneering force in cross-platform mobile development, Microsoft has officially transitioned its evolution into .NET MAUI (Multi-platform App UI), which extends the cross-platform capability beyond mobile to include desktop (Windows and macOS) applications. Developers with existing Xamarin projects are encouraged to migrate to .NET MAUI, which carries forward Xamarin's core principles while offering a modernized architecture and broader platform support.