Google ReCaptcha Implementaion in ASP.Net

.aspx

<%@ Register TagPrefix="recaptcha" Namespace="Recaptcha" Assembly="Recaptcha" %>

<form id="form1" runat="server">

    <div>

        <recaptcha:RecaptchaControl ID="recaptcha" runat="server" PublicKey="6LfG4dcSA A A A A Lm Tx u3m X l s 18bOCLDX rBfhy -opZ"

            PrivateKey="6LfG4dcSA A A A A DW1NEM z A 1V 2cM Jx F2EwX M dz X Em I" />

        <asp:PlaceHolder ID="Pholder" runat="server"></asp:PlaceHolder>

    </div>

    <div>

        <asp:Button ID="btncheck" runat="server" Text="Submit" OnClick="btncheck_Click" />

        <br />

        <asp:Label ID="lblerr" runat="server" ForeColor="Red"></asp:Label>

    </div>

    </form>

.aspx.cs

//This is for dynamic Recaptcha Creation

        protected void Page_Init(object sender, EventArgs e)

        {

            Recaptcha.RecaptchaControl rec = new Recaptcha.RecaptchaControl();

            rec.ID = "recaptcha";

            rec.PublicKey = "6LfG4dcSA A A A A Lm Tx u3m X l s 18bOCLDX rBfhy -opZ";

            rec.PrivateKey = "6LfG4dcSA A A A A DW1NEM z A 1V 2cM Jx F2EwX M dz X Em I";

            Pholder.Controls.Add(rec);

        }

protected void btncheck_Click(object sender, EventArgs e)

        {

            if (Page.IsValid)//You can use directly recaptcha.IsValid but it won't check for whole Page

            {

                lblerr.Text = "Valid Submission";

            }

            else

            {

                lblerr.Text = "In Valid Submission";

            }

        }

You Can Download the Working Code of Google ReCaptcha Implementaion in ASP.Net From here.

You Can Download the Working Code of Captcha in ASP.Net From here.