Count number of current users / sessions - Asp.Net

There are a few ways you can approach this. One is to track users using global.asax and an application variable.

Add Global.asax file to your website / web application.

------------
C# Code :
------------

        protected void Application_Start(object sender, EventArgs e)
        {
            Application["SessionCount"] = 0;
        }

        protected void Session_Start(object sender, EventArgs e)
        {
            Application.Lock();
            Application["SessionCount"] = Convert.ToInt32(Application["SessionCount"]) + 1;
            Application.UnLock();
        }

        protected void Session_End(object sender, EventArgs e)
        {
            Application.Lock();
            Application["SessionCount"] = Convert.ToInt32(Application["SessionCount"]) - 1;
            Application.UnLock();
        }

----------------
VB.Net Code : 
----------------

        Protected Sub Application_Start(sender As Object, e As EventArgs)
     Application("SessionCount") = 0
        End Sub

        Protected Sub Session_Start(sender As Object, e As EventArgs)
    Application.Lock()
           Application("SessionCount") = Convert.ToInt32(Application("SessionCount")) + 1
    Application.UnLock()
       End Sub

       Protected Sub Session_End(sender As Object, e As EventArgs)
    Application.Lock()
    Application("SessionCount") = Convert.ToInt32(Application("SessionCount")) - 1
    Application.UnLock()
      End Sub

Then, in any page you can get current count of number of users:

<asp:Label ID="CounterLabel" runat="server" 
    Text='<% Response.Write("Current session count: " + Application["SessionCount"]) %>' />