There are several places on the Internet today where it might make sense to look for some extra info about captchas.
No single website is perfect (ours included), so if you're serious about knowing your captchas, do the homework.
Captcha.org Homepage captcha.org
Captcha.org is a quite comprehensive but outdated list of captchas that can be used from ASP and ASP.NET.
Actually, captcha.org belongs to us.
Also, you know that huge chasm that exists between wishful thinking and reality? Captcha.org slipped into it big time.
We underestimated the amount of work that such a site requires by an order of magnitude. And we overestimated the amount of work that we will be able to dedicate to it by another order of magnitude.
The end-result of those miss-estimations is clearly visible: What was originally envisioned to be one-stop entry into the world of captcha became a somewhat outdated list of ASP.NET and ASP captchas :(
Hopefully, down the road we will have more time to dedicate to making it into a universally usable captcha resource.
reCAPTCHA Homepage recaptcha.net
If we only consider the ASP & ASP.NET captcha space, reCAPTCHA is actually the only BotDetect competitor worth a mention.
Don't get us wrong, it is not that we respect reCAPTCHA as a particularly good captcha implementation. In fact we do not, not at all.
We consider reCAPTCHA to be an extremely end-user-unfriendly security disaster just waiting to happen.
However, we do respect the market footprint that reCAPTCHA has established. And above everything else, we respect the CMU public relations team that accomplished it.
If you wish to explore the possibility of torturing your hard-won visitors, prospects and customers with two-words-long illegible captchas for the sole benefit of Google shareholders — feel free to dig into it.
Wikipedia article on Captcha wikipedia.org
The English version of Wikipedia article about captchas used to be about the only place where you could find some captcha information. It was all in one place. And it was sorted in a reasonable manner. Too bad that (unlike wine) it didn't age well.
During the period that started in May 2007 and lasted until September 2009, what was once upon a time an encyclopedia-style article about captchas — gradually became a reCAPTCHA marketing brochure.
It was a singularly outstanding piece of 'objective' work done by Wikipedia's captcha article editors of that time. Hats down folks.
Recently, someone finally started fixing the problem so the situation became significantly better compared to what it used to be in September 2009.
However, completely kicking reCAPTCHA out of the article, or including other captchas with significant market share is yet to be done.
Released in 1998, ASP (Active Server Pages) was Microsoft's first server-side script engine for dynamically-generated web pages. ASP is currently in version 3.0 with no further versions planned by Microsoft. Our BotDetect ASP CAPTCHA is a COM CAPTCHA Component that can be used by ASP programmers.
For more info about ASP one should probably take a look at the following sites:
Wikipedia article on ASP wikipedia.org
ASP documentation at MSDN microsoft.com
Microsoft released ASP.NET in 2002, as the direct successor of ASP. ASP.NET is currently in version 3.5 with version 4.0 scheduled for release during 2010. Any of the numerous .NET programming languages can be used for programming ASP.NET applications. However, the two programming languages most commonly used for web applications are C# and VB.NET. Our BotDetect ASP.NET CAPTCHA is a .NET CAPTCHA Control written in C# that be used by ASP.NET programmers.
For more info about ASP.NET one should probably take a look at the following sites: