Disclaimer: This post is an attempt to make a quick review of a rather shady material, such as captcha solvers. Please note, that I am absolutely sure that this sort of marketing tools can be used for research purposes only. Hope this text presents to be useful. CAPTCHA solvers can be used both for white hat and black hat SEO. The most reasonable use of it is in SERPtrackers, while there is almost no limit of expression for spammers and even hackers, so like any good thing this can be used for good and for bad. At the same time webmasters mostly hate those tools, especially if they have no knolege of the positive effect SEO automation can provide. All they sadly see in it are 'damn spammers'. Urban myths: There has been a rumor that human-powered CAPTCHA solving started on adult websites. Users had to insert CAPTCHA between the short videos, and then this was real CAPTCHA solved for other purposes. However, this myth reflects the attitude towards CAPTCHA solving as something mean, absolutely related with adult sites like it should be in the case of viruses, scam and... solving images. On the contrary, from the technical point of view, this sort of scam is useless. Human or OCR: differenciation and combination CAPTCHA solvers differ in two ways: either it is optical recognition software (OCR) or it's a human-powered online service. OCR is usually one-time fee, when you purchase the software, and then you solve CAPTCHAs 'for free' yet its accuracy is not that high. Most of software that needs CAPTCHA cracking uses the option of sending complicated CAPTCHAs to an online human-powered service via API. Human-powered CAPTCHA solving services are typical microjobs services where workers enter online or via special software and then thy are presented CAPTCHA images one by one. Their task is to return the picture in the form of the text or numbers with high speed and accuracy. Usually, average speed varies between 10-15 seconds and the accuracy of this type of services goes up to 95-98% Nevertheless, the price goes up too. It can be $1-12 per 1k CAPTCHAs which can result in $300-400 monthly budget in case you have several websites to promote. CAPTCHA Marketing One of the craziest ways to use CAPTCHA is so-called CAPTCHA-marketing. Somebody thought it could be a great idea to insert brand recognition into the CAPTCHA, because at the stage of inserting CAPTCHA the user is already involved in some type (type! what a word game!) of activity. Despite what the ad sais about this type of commercial campaigns, no this is not "really great advertising". People hate CAPTCHA, the very need to insert it provoques negative emotions which, therefore, will be associated with the brand. Unfortunately, I can quote no human CAPTCHA solving services which could solve this type of dreadful CAPTCHA. This video exmplains how it works: Other Types of CAPTCHA More typically, CAPTCHAs have the parameters listed below. Human-recognition services vary on the basis of their ability to solve CAPTCHAs with those parameters attribuated to them. Here is the list: Latin Numeric One or two words Math CAPTCHA Case Sensitive Pictures ReCaptcha – stands aside Plus, we may add such exotic types of CAPTCHA like Cyrillic, for example, used for some eastern Europe SE, like Yandex. What types of software need CAPTCHA solvers Mostly it is black hat SEO and spamming software: that is what produces the negative opinion about the service use. This list is not complete, of course, you can add something in the comments section, if you will, and I will add it here.. SERP trackers Link Building software Account registering software Posting software Directory submitting software Downloaders List of CAPTCHA bypass services DeathByCaptcha – Combines OCR with human service, one of the most known. Has limitations (for example, it doesn’t solve case sensitive CAPTCHA, as it is officially claimed on the website, even though on SEO forums they claim that they try to implement case sensitive options). 2Captcha.com – Relatively new service, the cheapest amongst human-powered ones ($0.6 per 1k). The service owners claim that unlike other services, they have scattered their workforce over the globe, that is how they both support the peak hours and keep the price low. De-captcher – The most expensive service from the range, especially with its fight for priority feature. Indeed, when the service capacity is like 123% during the afternoon UTC, the one who gives the biggest bid gets the CAPTCHAs solved first. The prepare-your-purses service, yet with good stability and accuracy rate. Antigate - The second most expensive: while the website says it's only $0.7 per 1k, it has hidden costs so the true price is about $3-4. Has the same API that 2Captcha.com, also DBC has its own API and the Antigate's one. Can be replaced by any of those services. To my knowledge, other services provide OCR, please correct me if I'm wrong. Let's play around: All the 3 types of services listed above, different types of API yet they are re-worked so that you can replace one solution with another (DBC or 2captcha.com or de-captcher or Antigate, don't know about Captcha Bypass). All of them can be connected to the same software which can be used in the combination with OCR. How can it be practically used? 1. Set the bid limit for each service. (See interface). When the bid exceeds your normal vision of reasonable price for human CAPTCHA solving, the service will deny request and the software will go to another service. 2. Add the services to the software so that when one is not responding, you can go to another one. 3. Leave simple CAPTCHAs to OCR, send only 'complicated CAPTCHAs' to humans. This way you can both help yourself and help the captcha services. On peak hours they have too many requests, so what they usually suggest on their websites is to preferably use the service at night when it's day in their solvers local area. I myself find it more reasonable to combine services. Also, take it into the consideration that mostly workers are located in one area. Amongst the human-powered services I found only 2captcha.com which says to have its workers over the globe in different time zones which reduces the peak hours turn offs possible risks. Hope this short review is somehow useful. I don't prenend to be the top savvy, trying to gather it all in one place only. If you have what to add or find that i am deeply wrong in something, you're very welcome both with valuable comments and unhealthy criticism.
Lots of great information about the CAPTCHA topic here and learned quite new things, I tried softwares to solve captcha but the success rate is real low and this needs to be done manually.
Many more OCR services are available as example 9kw.eu but google has really many more services in the results.
OCR services can do nothing with the new reCAPTCHA based on images while human workers are humans so thy can solve it and send the answer to the system. As far as I know only 2Captcha can currently do it.
Also, for your information: user Khivrin is an owner of 2captcha.com (WHOIS: http://whois.domaintools.com/2captcha.com)
Avoid death by captcha at all costs, they're the worse captcha service in the history of captcha services, the website is a joke they're also a bunch of thieves at DBC, they stole my $35 in captcha's, i have not used any captcha's in over 9 months because i have not needed to use them and when i went back to check my death by captcha account afew days ago all my $35 in captcha's were all gone! lol after i contacted this moron named john from death by captcha he pretty much told me that it was my! problem, to bad they're a bunch of crooks, never use there service, save your money and use a reputable and honest captcha service instead