Few technologies have ever been so disliked by both those who enforce its use and those upon whom its use has been enforced — yet so widely adopted as captcha.

With the spam flood at the website gates, and no viable alternatives anywhere in sight, webmasters are simply left without a choice — and millions of captchas are being solved every day.

Whether you like it or not — welcome to the world of CAPTCHA.

Captcha Directory

Q: So, what goes into this captcha directory?
A: According to its name the captchas will be an easy answer.

Q: But what a captcha is? How is it defined for the purpose of this directory?
A: If there is something that users have to solve... — it will satisfy a captcha definition.

Q: So, all captcha-enabled form processing and CMS software also qualifies?
A: No, packaging is also a factor. It must be stand-alone captcha software or captcha service built with the purpose of being embedded into something else.

Q: Anything else?
A: Captcha breakers and captcha alternatives are also welcome.

Captcha Software

Q: What fits within a captcha software description? Distorted text type captchas only, or there is room for other types as well?
A: It is open to all non-trivial types of captcha software.

Q: What about new conceptual captchas with less then perfect software implementations?
A: Even for them. If the concept is interesting and theoretically provides a reasonable level of protection, it can find its place here.

BotDetect PHP CAPTCHA

Version3.0.Beta1
StatusActive
Release Date2013-05-29
Product Homepagecaptcha.com/php-captcha.html
Online democaptcha.com/demo
Software LicenceCommercial
List priceFree, $69 - $499
Free trialYes
VendorCaptcha, Inc.
Vendor homepagecaptcha.com
Captcha Algorithms60
Sound supportYes
Reload buttonYes
Programming languagePHP
Source code availableYes
Captcha typeDistorted Text
Product typePHP CAPTCHA Library
OS supportWindows, OSX, Linux
64-bit supportYes
DependenciesPHP, libgd, mbstring
Inherited
IDE supportAny PHP Editor
Language APIsPHP
CMS pluginsWordPress, CakePhp, CodeIgniter

last updated on 2014/02/25 17:15

BotDetect ASP.NET CAPTCHA

Version3.0.14
StatusActive
Release Date2013-05-29
Product Homepagecaptcha.com/asp.net-captcha.html
Online democaptcha.com/demo
Software LicenceCommercial
List priceFree, $69 - $499
Free trialYes
VendorCaptcha, Inc.
Vendor homepagecaptcha.com
Captcha Algorithms60
Sound supportYes
Reload buttonYes
Programming languageC#
Source code availableYes
Captcha typeDistorted Text
Product typeASP.NET CAPTCHA Component
OS supportWindows
64-bit supportYes
Dependencies.NET Framework
Inherited
IDE supportVisual Studio 2003, Visual Studio 2005, Visual Studio 2008, Visual Studio 2010, Visual Studio 2012, Visual Studio 2013
Language APIsASP.NET
CMS pluginsNone

last updated on 2014/02/25 17:15

BotDetect ASP CAPTCHA

Version3.0.14
StatusActive
Release Date2013-05-29
Product Homepagecaptcha.com/asp-captcha.html
Online democaptcha.com/demo
Software LicenceCommercial
List priceFree, $69 - $499
Free trialYes
VendorCaptcha, Inc.
Vendor homepagecaptcha.com
Captcha Algorithms60
Sound supportYes
Reload buttonNo
Programming languageC#
Source code availableYes
Captcha typeDistorted Text
Product typeCOM CAPTCHA Component
OS supportWindows
64-bit supportYes
DependenciesNone
InheritedN/A
IDE supportN/A
Language APIsCOM, ASP
CMS pluginsNone

last updated on 2014/02/25 17:15

ASP Security Image Generator

Version2.0
StatusR.I.P.
Release Date2006-04-09
Product Homepagewww.tipstricks.org
Online demowww.tipstricks.org/example.asp
Software LicenceCommon Public License
List priceFree
Free trialYes
VendorEmir Tüzül
Vendor homepageUnknown
Captcha AlgorithmsUnknown
Sound supportNo
Reload buttonNo
Programming languageASP
Source code availableYes
Captcha typeDistorted Text
Product typeASP CAPTCHA Script
OS supportWindows
64-bit supportUnknown
DependenciesUnknown
InheritedN/A
IDE supportUnknown
Language APIsASP
CMS pluginsUnknown

last updated on 2007/12/19 14:38

Captcha ASP Script

Version1.0
Status
Release Date2006-10-31
Product Homepagewww.motobit.com/util/captcha
Online demowww.motobit.com/util/captcha
Software Licence
List priceFree
Free trialYes
VendorMotobit Software
Vendor homepagewww.motobit.com
Captcha Algorithms
Sound supportNo
Reload buttonNo
Programming languageVB Script
Source code availableYes
Captcha typeUndistorted Text
Product typeASP Captcha Script
OS supportWindows
64-bit supportUnknown
DependenciesOWC
Inherited
IDE support
Language APIs
CMS plugins

last updated on 2007/10/14 04:01

CAPTCHA Image

Version1.01
Status
Release Date2004-02-02
Product Homepagewww.codeproject.com/aspnet/captchaimage.asp
Online demoNot Available
Software Licence
List priceFree
Free trialYes
VendorBrainJar
Vendor homepagewww.brainjar.com
Captcha Algorithms
Sound supportNo
Reload buttonNo
Programming languageC#
Source code availableYes
Captcha typeDistorted Text
Product typeC# Captcha Class
OS supportWindows
64-bit supportYes
Dependencies.NET Framework
Inherited
IDE support
Language APIs
CMS plugins

last updated on 2007/10/14 03:57

CAPTCHA Server Control for ASP.NET

Version2.1
StatusActive
Release Date2007-01-29
Product Homepagewww.codeproject.com/aspnet/CaptchaControl.asp
Online demo
Software Licence
List priceFree
Free trialYes
VendorJeff Atwood
Vendor homepagewww.codinghorror.com
Captcha Algorithms
Sound supportNo
Reload buttonNo
Programming languageVB.NET
Source code availableYes
Captcha typeDistorted Text
Product typeASP.NET Captcha Component
OS supportWindows
64-bit supportYes
Dependencies.NET Framework
Inherited
IDE support
Language APIsASP.NET
CMS plugins

last updated on 2007/10/20 13:42

Floresense CAPTCHA control for ASP.NET

Version1.0
StatusActive
Release Date2007-08-20
Product Homepagewww.floresense.com/controls/dN/captcha/index.php
Online demo
Software LicenceCommercial
List priceFree, $16
Free trialYes
VendorFloresense Solutions
Vendor homepagewww.floresense.com
Captcha Algorithms
Sound supportNo
Reload buttonNo
Programming language
Source code availableNo
Captcha typeDistorted Text
Product typeASP.NET CAPTCHA Control
OS supportWindows
64-bit supportUnknown
Dependencies.NET Framework 2.0
Inherited
IDE support
Language APIs
CMS plugins

last updated on 2007/10/20 13:42

NetXtreme/AspXtreme CAPTCHA

VersionAll versions
StatusR.I.P.
Release Date
Product Homepage
Online demo
Software Licence
List price
Free trial
VendorSafaByte, ComponentForge, XtraComponents
Vendor homepageEver-changing
Captcha Algorithms
Sound support
Reload button
Programming language
Source code available
Captcha type
Product type
OS support
64-bit support
Dependencies
Inherited
IDE support
Language APIs
CMS plugins

last updated on 2010/04/13 12:30

NetXtreme/AspXtreme CAPTCHA is Lanapsoft's BotDetect ASP.NET CAPTCHA rip-off based on a decompiled BotDetect CAPTCHA source code. Unlike original, AspXtreme CAPTCHA lacks a few features that 'the vendor' couldn't figure out, and is enhanced with multiple bugs not present in the original version. Stay away from it.

More about this particular rip-off, as well as about numerous other rip-offs done by the same 'vendor' with an ever changing name/brand and URL you can find at http://cheated.by.safabyte.net/.

Some folks find weird ways for making money.

Text Disguise CAPTCHA Component

Version1.0.0
Status
Release DateUnknown
Product Homepagewww.textdisguise.com
Online demowww.textdisguise.com/TextDisguise/Demo.aspx
Software LicenceCommercial
List priceFree, $49 - $159
Free trialYes
Vendor27 Seconds, Inc.
Vendor homepagewww.27seconds.com
Captcha AlgorithmsUnknown
Sound supportNo
Reload buttonNo
Programming languageVB.NET
Source code availableYes
Captcha typeDistorted Text
Product type.NET CAPTCHA Component
OS supportWindows
64-bit supportYes
Dependencies.Net Framework
InheritedN/A
IDE supportUnknown
Language APIs.NET
CMS pluginsNone

last updated on 2007/10/11 00:45

The ASP CAPTCHA Project

Version0.1
Status
Release Date2005-06-07
Product Homepagewww.planet-source-code.com/vb/scripts/ShowCode.asp ?txtCodeId=9204&lngWId=4
Online demoNot Available
Software LicenceGPL
List priceFree
Free trialYes
VendorCS Shyam Sundar
Vendor homepagecsshyamsundar.wordpress.com
Captcha AlgorithmsUnknown
Sound supportNo
Reload buttonNo
Programming languageASP, VBScript
Source code availableYes
Captcha typeDistorted Text
Product typeASP CAPTCHA Script
OS supportWindows
64-bit supportUnknown
DependenciesGD by Thomas Boutell., GD is copyright 2005 Boutell.com, Inc. ActiveX Wrapper For GD by Trevor Herselman
InheritedNone
IDE supportNone
Language APIsASP
CMS pluginsNone

last updated on 2007/10/10 23:43

u229.no Captcha.asp

VersionUnknown
Status
Release Date2005-07-01
Product Homepagewww.u229.no/stuff/Captcha
Online demowww.u229.no/stuff/Captcha
Software LicenceUnknown
List priceFree
Free trialYes
Vendoru229.no
Vendor homepagewww.u229.no
Captcha AlgorithmsUnknown
Sound supportNo
Reload buttonNo
Programming languageASP, CSS, JavaScript
Source code availableYes
Captcha typeSimple Question
Product typeASP CAPTCHA Script
OS supportWindows
64-bit supportUnknown
DependenciesUnknown
InheritedN/A
IDE supportUnknown
Language APIsASP
CMS pluginsUnknown

last updated on 2007/10/10 23:43

Web Wiz CAPTCHA

Version3.0
Status
Release Date2007-07-22
Product Homepagewww.webwizcaptcha.com
Online demowww.webwizguide.com/webwizcaptcha/demo
Software LicenceCommercial
List priceFree, $15 - $100
Free trialYes
VendorWeb Wiz
Vendor homepage
Captcha AlgorithmsUnknown
Sound supportNo
Reload buttonYes
Programming languageASP
Source code availableUnknown
Captcha typeDistorted Text
Product typeASP CAPTCHA Component
OS supportWindows
64-bit supportUnknown
Dependencies
InheritedN/A
IDE support
Language APIsASP
CMS plugins

last updated on 2007/10/11 01:58

Captcha Services

Q: What is a captcha service? How is it defined for the purpose of this directory?
A: If the task users have to solve is generated and in the real-time delivered to the requesting user or website by a third-party... — it will satisfy a captcha service definition.

Q: What about packaging?
A: Same as anywhere else within directory — only stand-alone captcha services built with the purpose of being embedded into something else. No form-processing services, please.

captcha.cc

VersionN/A
StatusActive
Release Date2008-10-09
Product Homepagewww.captcha.cc
Online demoYes
Software LicenceN/A
List priceFree
Free trialYes
VendorDocument Root, Inc.
Vendor homepagewww.documentroot.com
Captcha AlgorithmsN/A
Sound supportYes
Reload buttonYes
Programming languagePerl
Source code availableNo
Captcha typeDistorted Text
Product typeCAPTCHA Service
OS supportN/A
64-bit supportN/A
DependenciesN/A
InheritedN/A
IDE supportUnknown
Language APIsASP, Python, PHP, ColdFusion, Perl, Java, Ruby
CMS pluginsNone supplied

last updated on 2009/06/04 10:39

Captchas.net

VersionUnknown
Status
Release DateUnknown
Product Homepagecaptchas.net
Online demoNo
Software LicenceN/A
List priceFree, $160/year
Free trialYes
VendorFelix Holderied & Sebastian Wilhelmi
Vendor homepageholderied.de, seppi.de/index.html.en
Captcha AlgorithmsUnknown
Sound supportYes
Reload buttonNo
Programming languageUnknown
Source code availableNo
Captcha typeDistorted Text
Product typeCAPTCHA Service
OS supportN/A
64-bit supportN/A
DependenciesN/A
InheritedN/A
IDE supportNone
Language APIsN/A
CMS pluginsPlone

last updated on 2007/10/11 02:06

reCAPTCHA

VersionN/A
Status
Release DateUnknown
Product Homepagewww.recaptcha.com
Online demorecaptcha.net/learnmore.html
Software LicenceN/A
List priceFree
Free trialYes
VendorCarnegie Mellon University
Vendor homepagewww.cmu.edu
Captcha AlgorithmsUnknown
Sound supportYes
Reload buttonYes
Programming languagePython
Source code availableUnknown
Captcha typeDistorted Text
Product typeCAPTCHA Service
OS supportN/A
64-bit supportN/A
DependenciesN/A
InheritedN/A
IDE supportUnknown
Language APIsPHP, Python, Perl, Ruby, Java, ColdFusion
CMS pluginsWordPress, MediaWiki, phpBB, Movable Type, Drupal, Symphony, Typo3, NucleusCMS, vBulletin, Joomla

last updated on 2007/10/14 04:03

Spamerator

Version
Status
Release DateUnknown
Product Homepagewww.spamerator.com
Online demoNone
Software LicenceN/A
List priceFree
Free trialN/A
Vendor
Vendor homepage
Captcha Algorithms
Sound supportNo
Reload buttonNo
Programming language
Source code availableN/A
Captcha typeUndistorted Text
Product typeCAPTCHA Service
OS supportN/A
64-bit supportN/A
DependenciesN/A
InheritedN/A
IDE supportN/A
Language APIsPHP
CMS pluginsNone

last updated on 2007/10/14 04:01

Text Disguise CAPTCHA Service

Version1.0.0
Status
Release DateUnknown
Product Homepagewww.textdisguise.com
Online demowww.textdisguise.com/TextDisguise/Demo.aspx
Software LicenceN/A
List priceFree
Free trialYes
Vendor27 Seconds, Inc.
Vendor homepagewww.27seconds.com
Captcha AlgorithmsUnknown
Sound supportNo
Reload buttonNo
Programming languageVB.NET
Source code availableNo
Captcha typeDistorted Text
Product typeSOAP CAPTCHA Service
OS supportN/A
64-bit supportN/A
DependenciesN/A
InheritedN/A
IDE supportUnknown
Language APIsSOAP API
CMS pluginsNone

last updated on 2007/10/11 00:46

Captcha Breakers

Q: If this is a captcha directory, why are captcha breakers allowed at all?
A: Because one who is in the process of making a decision to deploy a captcha needs to know about the current state of captcha breaking solutions — and then later to periodically re-asses its standing against them.

Q: What types of "captcha breakers" one can expect to see here?
A: Various types of captcha breaking research articles, software, services (even human based ones), etc.

aiCaptcha

Version
StatusInactive
Release Date2005-01-30
Product Homepagewww.brains-n-brawn.com/aicaptcha
Online demoNo
Software Licence
List price
Free trialNo
VendorCasey Chesnut
Vendor homepagewww.brains-n-brawn.com
Captcha AlgorithmsN/A
Sound supportN/A
Reload buttonN/A
Programming language
Source code availableNo
Captcha typeCaptcha Breaker
Product typeComment Spam Bot
OS support
64-bit supportN/A
Dependencies
Inherited
IDE support
Language APIs
CMS plugins

last updated on 2007/11/16 10:59

aiCaptcha is an excellent and easy to read article that includes a step by step guide on breaking of a particular weak captcha with some serious stuff — but without any rocket science involved in the process. And exactly because of that lack of rocket science aiCaptcha is a must read for anyone thinking about deploying captchas.

Even if you are not going to understand just about everything that is written in the article, aiCaptcha will make you able to recognize a lot of weaknesses in algorithms of many captchas that are available on the market today. In turn, you will be able to avoid deploying those weak captchas on your website.

aiCaptcha source code and executables are not available to the public.

CAPTCHA Killer

Version
StatusUnknown
Release DateUnknown
Product Homepagewww.captchakiller.com
Online demo
Software Licence
List price
Free trialYes
Vendor
Vendor homepagewww.captchakiller.com
Captcha AlgorithmsN/A
Sound supportN/A
Reload buttonN/A
Programming language
Source code availableNo
Captcha typeCaptcha Breaker
Product typeRESTfull CAPTCHA Breaking Service
OS support
64-bit supportN/A
Dependencies
Inherited
IDE support
Language APIs
CMS plugins

last updated on 2007/11/17 04:41

The long-term status of Captcha Killer is a bit unclear at this moment.

While the CaptchaKiller website does not state anywhere that the Captcha Killer is, or will be, out of business — the guy's post made 2007/09/24 clearly states:

"I'm facing legal trouble in the US. Can someone please help me move this company offshore? Any tips? Who should I be talking to?"

It seems that Captcha Killer got at least the MySpace legal team on its back and is now thinking about relocation. According to another post, the most likely destination is Panama.

Unfortunately, Captcha Killer says nothing about their captcha breaking technology :(

CaptchaSolver

Version
StatusR.I.P.
Release DateUnknown
Product HomepageURL used to be: www.captchasolver.com
Online demo
Software Licence
List price
Free trialN/A
Vendor
Vendor homepageURL used to be: www.captchasolver.com
Captcha Algorithms
Sound supportN/A
Reload buttonN/A
Programming language
Source code availableNo
Captcha typeCaptcha Breaker
Product typeCaptcha breaking sweat-shop with Web Service API
OS support
64-bit supportN/A
Dependencies
Inherited
IDE support
Language APIs
CMS plugins

last updated on 2007/12/22 06:32

CaptchaSolver seems not to exist any more. The website is down, and we do not think that we are going to hear about it again. At present, it is listed here only because of historical reasons.

CaptchaSolver used to be captcha-breaking sweat-shop. Numerous download sites still list CaptchaSolver API among their entries — but the download links lead to nowhere.

Hopefully, there will be someone out there who still has a copy of CaptchaSolver API. And if he/she is willing to forward it to captcha.org editors — in the future the CaptchaSolver entry might also get some educational reasons for its existence, beside the historical ones.

Google27

Version
Status
Release DateUnknown
Product HomepageURL is: google27.com/index.php?option=com_content& task=view&id=1&Itemid=9
Online demo
Software Licence
List price
Free trialNo
VendorGoogle27 Solution
Vendor homepageURL is: google27.com
Captcha Algorithms
Sound supportN/A
Reload buttonN/A
Programming language
Source code availableNo
Captcha typeCaptcha Breaker
Product typeCaptcha-breaking sweat-shop
OS support
64-bit supportN/A
Dependencies
Inherited
IDE support
Language APIs
CMS plugins

last updated on 2007/12/22 06:34

Google27 is just another of those shady captcha-breaking sweat-shop entities that claim to provide the dark-side with a technology and low-cost labor needed for bypassing captchas on high-value-target websites such are MySpace and Yahoo.

Google27 claims they will do, as a professional service, all the integration work between your existing bot software and their captcha-entry agents.

Google27 website seems to be banned from Google index so we are not providing a direct link to it. Use copy/paste instead. We simply do not want to take the risk and make Google algorithms nervous about our site as well. Ironically, it seems that Google does not ban Google27 from AdWords :)

PWNTCHA

VersionUnknown
Status
Release DateUnknown
Product Homepagesam.zoy.org/pwntcha
Online demoNo
Software LicenceUnknown
List priceN/A
Free trialNo
VendorSam Hocevar
Vendor homepagesam.zoy.org
Captcha AlgorithmsN/A
Sound supportN/A
Reload buttonN/A
Programming languageUnknown
Source code availableNo
Captcha typeCaptcha Breaker
Product typeNon-CAPTCHA Library
OS supportUnknown
64-bit supportUnknown
DependenciesUnknown
Inherited
IDE supportUnknown
Language APIsUnknown
CMS pluginsN/A

last updated on 2007/11/17 05:07

According to the PWNTCHA website PWNTCHA is 'simply a toolkit of image manipulation functions, and a list of known CAPTCHAs with the associated list of image operations to apply in order to decode each of them.'

So far we were unable to find the specifications of the PWNTCHA "toolkit". Also, we were unable to find PWNTCHA's "associated list of image operations to apply in order to decode each of them." Maybe we were looking on all the wrong places. Who knows.

If we were able to find those missing parts we would recommend PWNTCHA as a something that one interested in captchas should read. This way, there is really nothing to recommend.

PWNTCHA source code and executables are also not available to the public.

Captcha Alternatives

Q: If this is a captcha directory, why are captcha alternatives allowed at all?
A: Because there are some usage scenarios where a captcha alternative may solve at least a part of the same problems that captchas do.

Q: What types of captcha alternatives one can expect to see here?
A: For the time being it is only content-inspection type, with more types to follow on later.

Q: What about packaging?
A: Same as anywhere else within this directory, only stand-alone software or services built with the purpose of being embedded into something else.

Akismet

VersionN/A
Status
Release DateUnknown
Product Homepageakismet.com
Online demoN/A
Software LicenceN/A
List priceFree, $5 - $750+/month
Free trialYes
VendorAutomattic, Inc.
Vendor homepageautomattic.com
Captcha AlgorithmsN/A
Sound supportN/A
Reload buttonN/A
Programming languageUnknown
Source code availableNo
Captcha typeAlternative Technology
Product typeNon-CAPTCHA Service
OS supportN/A
64-bit supportN/A
DependenciesN/A
InheritedN/A
IDE supportUnknown
Language APIsPython, PHP, ColdFusion, Perl, Java, Ruby, Ruby on Rails, Lasso, .NET
CMS pluginsMovable Type, Drupal, phpBB, Blojsom, Bloxsom, Geeklog, Serendiptity, Nucleus, b2evolution, WordPress, PunBB, Expression Engine, Coppermine, Lifetype, Simple Machine Forums, Phorum, tDiary, MyBulletinBoard, PostNuke, Joomla, EZ Publish

last updated on 2007/11/09 21:38

Akismet might be an interesting captcha alternative for those folks to whom comment spam is the only problem caused by bots.

Technologically, Akismet is based on some form of automated spam-filtering. The self-correction of algorithms is made possible by the feedback that is constantly flowing-in through the built-in collaborative component.

If you are member of the above-mentioned group, and the web side of your business can survive some false positives and negatives that will inevitably keep happening forever as a result of Akismet's technological foundation, it might be worth to give Akismet a try.

While Akismet will not solve your spam problems, it will make living with them much easier.

Defensio

Version1.1
StatusActive
Release Date2007-11-07
Product Homepagedefensio.com
Online demo
Software Licence
List priceFree, $5 - $50+/month
Free trialYes
VendorKarabunga, Inc.
Vendor homepagekarabunga.com
Captcha Algorithms
Sound supportN/A
Reload buttonN/A
Programming language
Source code availableNo
Captcha typeAlternative Technology
Product typeNon-CAPTCHA Service
OS support
64-bit supportN/A
Dependencies
Inherited
IDE support
Language APIsRuby on Rails, .NET, Java, PHP
CMS pluginsWordPress, PixelPost

last updated on 2007/11/09 21:36

The word CAPTCHA is an acronym for "Completely Automated Public Turing test to tell Computers and Humans Apart."

Synonym wanna-be terms for captcha are numerous and nowhere even close of being in as widespread use. Some of those are Security Image Generator (SIG), Human Verification Test (HVT), and Human Interaction Proof (HIP), with the last one being favored by Microsoft.

More often captchas are simply incorrectly refered as security image, security code, security image code, turing test, reverse turing test, validation image, validation image code, image validation, verification image, verification image code, image verification, etc. While these terms when stretched may indeed describe a captcha they are primarily used as names for some other completely unrelated things.

Common misspellings for captcha are capatcha, captsha, capttcha, chaptcha, etc. together with their plural forms.

Few excerpts from the future captcha.org User Manual:

  • captcha.org editors are skeptic and somewhat poisonous by default
  • Captcha vendors are over-optimistic and upbeat by default
  • See what that particular captcha community thinks — if there is one :)

Captcha History:

If we put aside work done by Alan Turing in the 1950s, the first discussion of automated tests which distinguish humans from computers for the purpose of controlling access to web services is in the 1996 manuscript "Verification of a human in the loop, or Identification via the Turing Test" written by Moni Naor from the Weizmann Institute of Science.

For the information on what happened after that we suggest you to do the same thing that we do — stay tuned to the ever-changing 'origin' section of the captcha article on Wikipedia :)