Avoid Page refresh (reload) on RadioButton click when AutoPostBack is True in ASP.Net

You need to use ASP.Net AJAX UpdatePanel to avoid Page refresh.

<div>
    <asp:ScriptManager runat="server">
    </asp:ScriptManager>
    <asp:UpdatePanel runat="server">
        <ContentTemplate>
            <asp:RadioButton AutoPostBack="true" ID="rb1" Text="Radiobutton1" GroupName="rb"
                runat="server" OnCheckedChanged="Radiobutton1_CheckedChanged"></asp:RadioButton></td>
            <asp:RadioButton AutoPostBack="true" ID="rb2" Text="Radiobutton2" GroupName="rb"
                runat="server" OnCheckedChanged="Radiobutton2_CheckedChanged"></asp:RadioButton>
            <br />
            <asp:TextBox ID="TxtId" runat="server" Visible="false" Width="60px"></asp:TextBox>
            <br />
            <asp:TextBox ID="TxtName" runat="server" Visible="false" Width="30px"></asp:TextBox>
        </ContentTemplate>
    </asp:UpdatePanel>
</div>

C#

protected void Radiobutton2_CheckedChanged(object sender, EventArgs e)
{
    if (this.rb2.Checked)
    {
        this.TxtId.Visible = true;
    }
}

protected void Radiobutton1_CheckedChanged(object sender, EventArgs e)
{
    if (this.rb1.Checked)
    {
        this.TxtName.Visible = true;
    }
}