SharePoint Online AddIns

protected void Page_Load(object sender, EventArgs e)
        {
 
            var spContext = SharePointContextProvider.Current.GetSharePointContext(Context);

            using (var clientContext = spContext.CreateUserClientContextForSPHost())
            {
                clientContext.Load(clientContext.Site);
                clientContext.Load(clientContext.Web, web => web);
                clientContext.Load(clientContext.Web.Lists);
                clientContext.ExecuteQuery();
                ListBox1.Items.Add(clientContext.Site.Url);
                ListBox1.Items.Add(clientContext.Web.Title);
                ListBox1.Items.Add(clientContext.Web.Url);
            }
        }