ASP.NET AJAX Downloads
AJAX functionality is integrated in ASP.NET 3.5 and does not require any additional downloads.
In order to incorporate ASP.NET AJAX features in ASP.NET 2.0, download the ASP.NET AJAX Extensions 1.0 release or upgrade to ASP.NET 3.5.
ASP.NET AJAX Optional Components
ASP.NET AJAX Control Toolkit
The ASP.NET AJAX Control Toolkit is a joint project between the community and Microsoft that provides a rich array of controls for building interactive Web experiences easily.
Microsoft AJAX Library 3.5
Microsoft ASP.NET 3.5 Extensions Preview
ASP.NET AJAX Downloads for ASP.NET 2.0
ASP.NET AJAX Extensions 1.0
ASP.NET AJAX Extensions 1.0 enables ASP.NET AJAX features in ASP.NET 2.0. It integrates client script libraries with the ASP.NET 2.0 server-based development framework.
ASP.NET 2.0 AJAX Templates
If you are using Visual Studio 2008 or Visual Web Developer 2008 to create new Web sites and Web applications with ASP.NET 2.0 and ASP.NET AJAX Extensions 1.0 then install the ASP.NET 2.0 AJAX Templates for VS2008 below.