This is the official page of MS Captcha project, originally created by Mondor Software

It is maintained by me since November of 2011.

How Captcha looks like, simple form

Key features of Captcha ASP.NET Server Control:

  • Ability to set any size for your captcha
  • Set any alphabet (not necessarily English) and string length
  • Set the level of noise and line noise
  • Timer to make your captcha obsolete after specified period of time
  • Set various fonts for your captcha
  • Arithmetic functions require users to solve equations instead of simple typing
  • XHTML 1.1 compliant


Planned Enhancements of Captcha ASP.NET Control:

Captcha Adaptive Engine

Adaptive engine of MS Captcha is an additional layer of security - it checks whether your visitor is a known spammer and allows you to modify your web page or Captcha control accordingly. For example, you could either divert request / redirect it to another page, or just harden Captcha using alternative settings. E.g. if visitor is a suspect, you could show 5 letter-long Captcha instead of 3 letter-long, and add more noise or use arithmetic function. It will also set the property of Captcha control to indicate that the visitor is a potential violator, so you would be able to use that information in your workflow.
For example, if someone is trying to post a comment in your website, but Captcha says he is a known spammer, perhaps you would put his message on hold until your moderator reviews it and makes a decision.

  • HTML 5 compatible output
  • Audio playback of Captcha value
  • Different colors for each symbol
  • Random settings (noise, color etc) for each instance
  • Tool for automatic registration of component in ASP.NET project
  • Captcha proxy for centralized generation


Download the latest version of the Captcha ASP.NET Component.

Download older version 2.0, suitable for .NET Framework 2.0 and up.

Sample project is available in separate post about ASP.NET Captcha Sample.


MS Captcha is free to use in any kind of projects. The software is licensed, not sold.

Setting up

Reference .dll in your project

Modify web.config: add two handlers:

1. In <system.webServer><handlers> add this: <add name="MSCaptcha.captchaImageHandler" verb="GET" path="CaptchaImage.axd" type="MSCaptcha.captchaImageHandler, MSCaptcha" resourceType="Unspecified" />

2. In  <system.web><httpHandlers> add this: <add name="MSCaptcha" verb="GET" path="CaptchaImage.axd" type="MSCaptcha.captchaImageHandler, MSCaptcha" />

In web page, register control using this tag: <%@ Register Assembly="MSCaptcha" Namespace="MSCaptcha" TagPrefix="cc1" %>

Then add control like this: <cc1:CaptchaControl runat="server" ID="ccLink" CaptchaMaxTimeout="180" CaptchaMinTimeout="5" CaptchaLineNoise="Medium" CaptchaFontWarping="Medium" CaptchaLength="5" Arithmetic="true" Width="180px" />

Downloads (17.02 kb)

mscaptcha4.rar (19.86 kb)

See my other projects



blog comments powered by Disqus