Windows Software Development Kit (SDK) for Windows 8.1 is the latest version of Windows SDK that lets you develop Windows apps. The SDK for Windows 8.1 contains headers, libraries and tools you can use when you create apps, which run on Windows operating systems. You can use the Windows SDK, along with your chosen development environment to write Windows Store apps and desktop apps for Windows 8.1 as well as Windows 8, Windows Server 2012, Windows Server 2008 R2 and Windows Server 2008.