Display online users in in ASP.NET application

To display online users in ASP.NET application u need to add a Global.asax file. Global.ascx is the ASP.NET application file. It has some application level events raised by ASP.NET application. In the below code whenever a user log in to your application a count will increase in Application["CurrentUsers"] state. The count will decrease when he Log Out.

void Application_Start(object sender, EventArgs e)  
{  
    // Code that runs on application startup  
    Application["CurrentUsers"] = 0;  
}  

void Application_End(object sender, EventArgs e)  
{  
    // Code that runs on application shutdown  
}  

void Application_Error(object sender, EventArgs e)  
{  
    // Code that runs when an unhandled error occurs  
}  

void Session_Start(object sender, EventArgs e)  
{  
    // Code that runs when a new session is started  
    Application.Lock();  
    Application["CurrentUsers"] = (int)Application["CurrentUsers"] + 1;  
    Application.UnLock();  
}  

void Session_End(object sender, EventArgs e)  
{  
    // Code that runs when a session ends.  
    // Note: The Session_End event is raised only when the sessionstate mode  
    // is set to InProc in the Web.config file. If session mode is set to StateServer  
    // or SQLServer, the event is not raised.  
    Application.Lock();  

    if ((int)Application["CurrentUsers"] > 0)  
    {  
        Application["CurrentUsers"] = (int)Application["CurrentUsers"] - 1;  
    }  

    Application.UnLock();  
}  

Then in the Code behind add the below code

Label1.Text = Convert.ToString(Application["CurrentUsers"]);