In this post . Google ReCaptcha in Asp.Net

Google ReCaptcha is a free Servic from Google That Helps to protect website from spam and abuse that restricts the automated input sent by a system and allow only input from a real human.



Download ReCaptcha.Dll File From Google
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https://code.google.com/archive/p/recaptcha/downloads


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Create Google ReCaptcha Public and Private Key
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https://www.google.com/recaptcha/admin#site/339101101?setup

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Register Google ReCaptcha.dll file in Asp.Net Project
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<%@ Register TagPrefix="recaptcha" Namespace="Recaptcha" Assembly="Recaptcha" %>

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Coding For Google ReCaptcha User Control
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<asp:Panel ID="Panel1" runat="server">
            <recaptcha:RecaptchaControl  
    ID="recaptcha"  
    runat="server"  
    PublicKey="6LetRTYUAAAAAKJ21I_z4URdgpQwLtAbmixJT-Ca"  
    PrivateKey="6LetRTYUAAAAACU2vss8wjfIBbD3rPgTigVuNCGf"  
    /> 
 </asp:Panel>
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Submit Button Click Event Coding
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if (recaptcha.IsValid)
        {
            Label3.Text = "Successfully Validated";
            Panel1.Visible = false;
            Button1.Visible = false;



        }
        else
        {

            Label3.Text = "You are not Validated- Re-Enter Captcha Image Properly";


        }

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