Difference between Windows App SDK and WinUI 3

Question

I develop many UWP apps to Windows 10, but to Windows 11 I have so many questions and sometimes the Microsoft Docs it's confusing. I want develop new apps to Windows 11 but I am totally lost!

What is the difference between Windows App SDK and WinUI 3? I dont understand :(

And what is the best way to develop Windows 11 apps? Still UWP? Or Windows App SDK? Or WinUI 3?

UWP dont have round corners thats correct? I create a new project in my computer with Windows 11 in visual Studio 2022 and only the window of my app have rounder corners, but another elements (for example buttons) dont have rounded corners!

And Mica is not only availabe in WinUI 3?

Answer 1

The Windows App SDK is the next evolution in the Windows app development platform.

WinUI is the UI part of the Windows App SDK. It provides UI features for the Windows App SDK apps. When you create a Windows app SDK app, you have to use WinUI3 to create the UI layout. The previous version of WinUI like WinUI 2.7 could be used in UWP apps.

Using UWP or Windows App SDK depends on your own requirements and scenario, both of them could work on Windows 11.

Answer 2

Let me post an answer with some new information.

What is the difference between Windows App SDK and WinUI 3?

The Windows App SDK is the overall development platform for modern Windows desktop apps. It provides APIs, deployment tools, and system integrations. WinUI 3 is the UI layer within Windows App SDK. It gives you modern controls, styles, and fluent design for your app interface. So, WinUI 3 is PART of the Windows App SDK.

And what is the best way to develop Windows 11 apps? Still UWP? Or Windows App SDK? Or WinUI 3?

UWP is still supported but largely in maintenance mode. For new apps targeting modern Windows 11 features, I'd recommend WinUI 3 with the Windows App SDK. If you're looking for a mature ecosystem with extensive community tooling and legacy compatibility, WPF remains a solid choice.

This post should help.

FYI: WinUI 3 is moving toward open source, which may drive more community involvement and faster progress.

https://github.com/microsoft/microsoft-ui-xaml/discussions/10700#discussioncomment-13980717

UWP dont have round corners thats correct?

Yes and no. UWP apps use the older WinUI 2 library, which got rounded corner support starting with Windows 11—but it’s limited. Your app window may get the rounded look automatically, but individual controls (like buttons) won’t unless explicitly styled or updated with newer versions of WinUI 2.

And Mica is not only availabe in WinUI 3?

I haven't tried it but according to this doc, you can use Mica on UWP.