HttpRequest.AnonymousID Property


Gets the anonymous identifier for the user, if present.

Namespace:   System.Web
Assembly:  System.Web (in System.Web.dll)

Public Property AnonymousID As String
	Friend Set
End Property

Property Value

Type: System.String

A string representing the current anonymous user identifier.

The AnonymousID property assigns a long-lived unique identifier to a non-authenticated user, which can be used to track the user or assign profile properties to that user without storing data in a Session object. By default, the AnonymousID property is tracked using a cookie, but it can be set to use the URI when the Cookieless attribute in the anonymous identification configuration section is set to either the UseUri, UseDeviceProfile, or AutoDetect value. You must explicitly clear the cookie if you no longer want it available, for example when an anonymous user is authenticated.

Anonymous identification is used when there is a need to identify entities that are not authenticated and when authorization is required. For more information, see anonymousIdentification Element (ASP.NET Settings Schema)

The following example shows how to use the AnonymousID property by handling the Creating event in the Global.asax file. This example has two parts:

  • A method in the Global.asax file that handles the Creating event.

  • A Web Forms page.

The first part of the code example shows how to set the AnonymousID property by handling the Creating event in the Global.asax file. The method that is named AnonymousIdentification_Creating sets the AnonymousID property when an anonymous ID is created.

Sub Application_Start(ByVal sender As Object, ByVal e As EventArgs)

    'Initialize user count property
    Application("UserCount") = 0

End Sub

Sub AnonymousIdentification_Creating(ByVal sender As Object, ByVal e As AnonymousIdentificationEventArgs)

    ' Change the anonymous id
    e.AnonymousID = "mysite.com_Anonymous_User_" & DateTime.Now.Ticks

    ' Increment count of unique anonymous users
    Application("UserCount") = Int32.Parse(Application("UserCount").ToString()) + 1

End Sub

The second part of the code example shows how to display the new AnonymousID that is created by the AnonymousIdentification_Creating event handler in the preceding example.

<%@ Page Language="VB" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "">

<script runat="server">

  Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs)

    If (Application("UserCount") IsNot Nothing) Then
      lblUserCount.Text = Application("UserCount").ToString()
      lblCurrentUser.Text = Request.AnonymousID
    End If

  End Sub


<html xmlns="" >
<head id="Head1" runat="server">
    <title>AnonymousID Example</title>
    <form id="form1" runat="server">
        Number of users: 
        <asp:Label ID="lblUserCount" Runat="server"></asp:Label><br />
    Current user:
        <asp:Label ID="lblCurrentUser" Runat="server"></asp:Label><br />

.NET Framework
Available since 2.0

HttpRequest Class
System.Web Namespace
anonymousIdentification Element (ASP.NET Settings Schema)

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