adding an easy captcha tool

I have a site and i need to add a captcha in the end of my form. Any suggestion for an easy and simple captcha? I don't want to include dll .

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Kyle AbrahamsSenior .Net DeveloperCommented:
There's one on code project but it's not as easy as just plugging and playing.  You can follow along and tweak it if you want:

Any reason why you don't want to use a DLL?
shpresaAuthor Commented:
I tried that and it gives me

Parser Error Message: Could not load file or assembly 'WebControlCaptcha' or one of its dependencies. The system cannot find the file specified.
Kyle AbrahamsSenior .Net DeveloperCommented:
Well there's a lot more to it then that.  You need to add the source control project files to your solution.  

It might be easier to use a DLL . . . in which case I would recommend MSCaptcha:

Download here:

Example here:
Tapan PattanaikSenior EngineerCommented:
Hi shpresa ,

Add Captcha To Your ASP.Net WebForms Project :

I) Go to solution explorer and Right click on it.
ii)Click on “Manage Nuget Packages”
iii)Search for BotDetect and install the one that is created by Captcha,

Here is the code to display the captcha, write the below  code. (In your .ASPX page)

<asp:textbox ID="txtCaptcha" runat="server"></asp:textbox>
           <botdetect:captcha ID="captchaBox" runat="server"></botdetect:captcha>

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For .aspx.cs:

bool isHuman = captchaBox.Validate(txtCaptcha.Text);
            txtCaptcha.Text = null;
            if (!isHuman)
                //The Captcha entered by user is Invalid.
                //The Captcha entered by user is Valid.

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