This is the modern standard for .NET development. You can install it directly into your project via the NuGet Gallery . Command: Install-Package AjaxControlToolkit
For manual installation or older environments, you can download the compiled binaries from the official GitHub releases page . Latest Version: v20.1.0 (Released by DevExpress).
As of May 2026, the project is but remains available for reference and legacy use. Where to Download Ajax Control Toolkit DLL ajax control toolkit dll download
Older builds for .NET 3.5 or Visual Studio 2008 can be found on archived sites like ajaxtoolkit.net . Step-by-Step: Installing the DLL in Visual Studio
Once you have the DLL, follow these steps to integrate it into your development environment: This is the modern standard for
The is a widely used open-source library that simplifies the integration of AJAX-enabled controls into ASP.NET Web Forms applications. For developers maintaining legacy systems or building new Web Forms projects, downloading and correctly referencing the AjaxControlToolkit.dll is essential for enabling features like calendars, auto-completes, and modal popups without full page refreshes.
There are two primary ways to obtain the AjaxControlToolkit.dll : Latest Version: v20
Installing AJAX Tool Kit in Visual Studio 2013 - Stack Overflow