BotDetect ASP.NET CAPTCHA
BotDetect - ASP.NET CAPTCHA is a website security component designed to protect your registration, comment, and other online forms from automated spam submissions. It generates CAPTCHA images that easily tell bots and humans apart. 50 different CAPTCHA algorithms, custom size and image format, sound support that allows access even to visually impaired! 'Developer Edition' includes FULL SOURCE CODE and ROYALTY FREE distribution rights!