The ASP.NET AJAX Control Toolkit is an open-source project built on top of the Microsoft ASP.NET AJAX framework.
The ASP.NET AJAX Control Toolkit is a classic set of ASP.NET WebForms extensions. It has been used in a huge number of existing projects and remains popular till now. The Toolkit contains more than 40 controls, including the HtmlEditor, Accordion, AutoComplete, Calendar and ColorPicker controls integrated with the Visual Studio design time.
The project started as a joint effort between Microsoft and the ASP.NET AJAX community, but from September 2014 the project has a new owner, which is DevExpress.