Easy to use, ASP.NET Captcha Control, written in C#

By Vishal Khanna, 8th Aug, 09

Checkout an easy to use, simple ASP.NET CAPTCHA Control, free source code, you will be able to set up this captcha in 5 minutes, and further enhance the security of your website, protect spam. Code written in C#.

The code below taps the powers of C#.

Step 1: Create a web page by the name "Captcha.aspx". In the code behind of this page, paste the following code:

using System;

using System.Collections;

using System.Configuration;

using System.Data;

using System.Linq;

using System.Web;

using System.Web.Security;

using System.Web.UI;

using System.Web.UI.HtmlControls;

using System.Web.UI.WebControls;

using System.Web.UI.WebControls.WebParts;

using System.Xml.Linq;

using System.Drawing;

public partial class Captcha : System.Web.UI.Page

protected void Page_Load(object sender, EventArgs e)

this.returnNumer();

private void returnNumer()

Random num1 = new Random();

Random num2 = new Random();

int numQ1 = 0;

int numQ2 = 0;

string QString = null;

QString = numQ1.ToString() + " + " + numQ2.ToString() + " = ";

Session["answer"] = numQ1 + numQ2;

Bitmap bitmap = new Bitmap(85, 24);

Graphics Grfx = Graphics.FromImage(bitmap);

Font font = new Font("Arial", 18, FontStyle.Bold, GraphicsUnit.Pixel);

Rectangle Rect = new Rectangle(0, 0, 100, 50);

Grfx.FillRectangle(Brushes.BlueViolet, Rect);

Grfx.DrawRectangle(Pens.PeachPuff, Rect);

// Border

Grfx.DrawString(QString, font, Brushes.White, 0, 0);

Response.ContentType = "Image/jpeg";

bitmap.Save(Response.OutputStream, System.Drawing.Imaging.ImageFormat.Jpeg);