While originally maintained by Microsoft, the toolkit is now managed by DevExpress. 2. Add DLL to Visual Studio Toolbox
The easiest way to get the latest version (v20.1.0) is via the AjaxControlToolkit NuGet Gallery . Ajax Control Toolkit Dll File
If you download the ZIP file manually, you must right-click the file, select Properties , and click Unblock before extracting. While originally maintained by Microsoft, the toolkit is