//Get Application Instance from Current Content
HttpApplication httpApps = HttpContext.Current.ApplicationInstance;
//Get List of modules
HttpModuleCollection httpModuleCollections = httpApps.Modules;
Response.Write("Total Number Active HttpModule : " + httpModuleCollections.Count.ToString() + "</br>");
Response.Write("<b>List of Active Modules</b>" + "</br>");
foreach (string activeModule in httpModuleCollections.AllKeys)
{
   Response.Write(activeModule + "</br>");
}