Windows App SDK

Features and components

Most development effort for the decoupled UI stack has focused on bug fixes, debugging improvements, and simplifying window management through the shift from CoreWindow. An API called AppWindow abstracts USER32 and GDI32 primitives, providing a unified set of windowing capabilities and enabling custom window controls. A Chromium-based WebView2 control replaced the earlier UWP WebView, which relied on an unsupported browser engine; WebView2 works with WinUI and other supported app types.

MSIX is included as the recommended packaging format, but the SDK also supports unpackaged apps that can be deployed as self-contained or framework-dependent, with dynamic loading of app dependencies available for both packaged and unpackaged scenarios. DWriteCore offers decoupled, device-independent high-quality text rendering, and Win2D is available to WinUI 3 apps. MRT Core, a decoupled version of the UWP resource management system, handles app resources for localization and similar purposes.

Stable releases now include app lifecycle features such as power management notifications, rich activation, multiple instances, and programmatic app restart, which previously required significant developer effort in Win32 applications. Push notification APIs have been stabilized after initially being a limited-access preview, though Microsoft can revoke access at its discretion; local app notifications can be displayed without creating an XML payload.

Third-party integration with the Windows 11 Widgets system is part of the stable release channel, allowing developers to design custom widgets using adaptive cards and surface them on the widgets board.