Website security component designed to protect your registration forms, guestbooks, polls, and other online forms from automated spam submissions. 'Developer Edition' includes FULL SOURCE CODE and ROYALTY FREE distribution rights!   Code: ASP.NET v2.0 & C#

dotnetcaptcha is a web component for the .NET Framework that allows you to simply generate captcha images. There are multiple types of captcha image to choose from, and a unique feature that allows you to specify a mathematical captcha as well.   Code: ASP.NET v1.1 & VB

HTMLCaptcha randomly outputs a small icon-sized image -- a real picture, not skewed text -- created entirely in HTML/CSS, and then offers a random selection of descriptions. The user must select the correct descriptor in order to validate.   Code: ASP.NET v1.1 & C#

CaptchaControl is an ASP.NET server control that is designed to start working by just being dropping onto the page, without any modification. This version is based off Michael Trefry’s implementation, which is in turn based off Dan Burke’s.   Code: ASP.NET v2.0 & VB

Do you want a control that meets the following requirements: easy to use, only one assembly to reference, invisible, and works when javascript is disabled. The result is the Invisible Captcha control which is a validation control.   Code: ASP.NET v2.0 & VB