BotDetect CAPTCHA Generator Homepage

BotDetect™ CAPTCHA generator is a form security solution using Captcha challenges, that are easy for humans but hard for bots, to prevent automated page posting. Bots are kept from accessing protected website functionality using Captcha images specifically designed to be out of reach of computer vision and OCR technologies. BotDetect also provides an audio Captcha alternative enabling you to make WCAG and Section 508 compliant websites in order to keep your websites accessible to people with impaired vision.


A long time ago, spammers automated spamming by use of software robots (spam-bots). It costs them several orders of magnitude less to post a spam or open a spamming account than it costs you to manually weed it out.

Captcha is an equalizer. It levels the playing field by imposing real costs on spammers who have to employ human labor to solve them -- while slashing the cost for website operators who suddenly have orders of magnitude less spam to deal with.

Why BotDetect?

BotDetect is unique among Captcha generators in offering many Captcha image and sound styles. While each of them is easily comprehensible to human users, randomly using multiple Captcha generation algorithms makes the generated Captcha challenge practically impossible to pass automatically.

This approach to Captcha security is validated by the BotDetect track record: we have over 3000 paying customers and not one confirmed case of automated Captcha breaking by spammers.

Visual Studio 2015 & .NET 4.6 Ready

BotDetect ASP.NET CAPTCHA v3.0.16 supports the latest Microsoft Visual Studio 2015 and .NET 4.6 releases.

Full support for all Android & iOS devices

BotDetect CAPTCHA v3.0.13 audio now works on Android and iOS devices. Unlike other Captchas, sounds are played directly on the form page, without opening the media player app.

BotDetect CAPTCHA Features

BotDetect CAPTCHA Box
  • 60 secure & readable Captcha image styles
  • 10 secure & accessible audio Captcha sound styles
  • Localized Captcha generation, using various Unicode character sets and downloadable multi-language sound pronunciations
  • Custom Captcha image size, format, color scheme...
  • Custom Captcha code length, style, character set, timeouts, generated code filtering...
  • Many other randomization & customization options
  • Compatible with various MVC web application frameworks
  • Supports extra Ajax Captcha validation for improved form usability, through built-in JavaScript functionality and jQuery validation

BotDetect Captcha vs. Recaptcha

Some people might genuinely disagree, and the team 'dark side' would certainly work hard to frame it differently, but unfortunately the mainstream captcha market has dwindled down to only two viable options.

BotDetect and recaptcha, us versus them. So let's see how we stack up against each other.

1) BotDetect Does Not Spy

Unlike the recaptcha spyware joke, BotDetect doesn't operate under 'if we can doxx you then you are human' principles; and it will not leave you confused or puzzled when your application starts getting rejected by the most of world governments on the grounds of national security; be it on their own websites, or on the websites of their sensitive institutions and industries.

The US State Department, the US Supreme Court, the US Department of Homeland Security, and numerous other US federal agencies are all our esteemed paying customers.

But the FBI is a recaptcha user. One might say so the NSA can fill the 'invisible' part of that FBI form with the info that, in the US, would be either illegal to ask, or unlikely to be answered.

The NSA is almost promoting them. See this. No, there is no BotDetect on that list.

When you or Ms. Merkel encounter recaptcha, it access your cookies. The same ones used by other Google services. Some of those services carry enough info to identify you -- the other ones have a wide reach. Google went to great lengths to obfuscate the scripts used. So the scripts and cookies accessed can vary a lot among persons, sites, and ip addresses.

As long as the pages you and Ms. Merkel are accessing use recaptcha or some of those other services, the NSA will be able to brief Mr. President about what Ms. Merkel read or did on the web yesterday. And to tip-off the IRS what foreign e-banking systems you use. Or whoever else about your adult video preferences, where that webmail account is that you were so sure no one knew about, and that you just tipped-off the FBI about something. Ouch.

You see, you are not a robot -- and recaptcha is not a captcha -- it is just disguised as one.

You are a human being with privacy expectations -- and recaptcha is a mass-surveillance tool.

Does Google's top-brass knowingly and willingly play hand in hand with the NSA; so Google gets far better ad targeting, and the NSA gets an opportunity to either license, get through FISA court order, or somehow intercept the data feed?

Or it was just the sheer stupidity of authors of the recaptcha service architecture who put such a thing directly on domain, and in turn opened it up for the NSA use and abuse?

It is difficult to say and impossible to prove.

One way or another, we consider them to be the team we call the 'dark side'. And we consider recaptcha to be spyware -- 24/7 deanonymizing and prying on you, your visitors, users, and customers. Or even worse.

You decide for yourself.

2) BotDetect is a Safe Bet for the US Government Websites

BotDetect is Section 508 compliant and legal on the US federal agencies' websites -- unlike the above mentioned spyware of dubious legality that is just lame-ducking there while awaiting for its Section 508 lawsuit by a disgruntled employee or a user to throw it away.

Why is it like that? It is simple. When you block cookies in your browser, or go into incognito mode so the spyware cannot spy any more, it reverts back to the old recaptcha. And few things short of a miracle will make your application using the old recaptcha to be able to satisfy this particular Section 508 requirement.

Hopefully, it will not be your application underpinning the spyware when such a kind of accessibility suit hits. While the sue-ball itself will be directed toward a particular federal agency, it will be your application -- not the spyware -- alleged to be the Section 508 non-compliant.

You might have a hard time explaining the potential for those few extra millions in unbudgeted legal expenses to your other federal prospects.

One might say that the FBI was supposed to know the US laws somewhat better than what they demonstrated so far. We think so, too. But we guess the FBI has some other 'priorities'. :)

3) BotDetect Works in China

Oh, we almost forgot to mention, BotDetect works in China -- feel free to guess what particular 'captcha' doesn't :)

BotDetect CAPTCHA Customer References

Over the years, our products became a household name for high-quality Captcha components. Today, among our 3,000 customers, we are proud to have the following as our clients; Morgan Stanley, NASDAQ, Intuit, Con Edison, Accenture, Christie's Auctions, EMI Music, McNeil Consumer Healthcare, Swiss Telecom, and many more.