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Seems to me that they are an easy way out and band aid solution to a problem that could be solved in other ways. I have never implemented a captcha field on a website and do not intend to in the future, but I am curious when I see Google, Yahoo and eBay all using them. Surely there are better solutions to the problem.

As a user I find them incredibly frustrating even when they have been implemented well like reCaptcha and I am unlikely to convert if a site requires me to complete it. Surely there are many other users out there that will think the same.

Captcha are also not infallible with some spammers offering incentives for people to provide captcha answers in desktop apps.

With so many other options for traffic filtering/limiting is it just through laziness that we have ended up with so many out there or is there a reason I am missing?

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So what have you implemented to stop the spambots abusing the forms on the sites you've developed? –  ChrisF May 13 '11 at 12:35
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@ChrisF I have used varying techniques to limit spam coming through my systems. Granted these are more work than implementing captcha but they give the user a better experience which I value more highly. One such simple way would be to implement Defensio or Akismet. –  Treffynnon May 13 '11 at 13:21
    
Side note: Google has an obvious interest in reCaptcha. When they scanned millions of books into their network, some of the words were not digitally identifiable. TO solve the problem, they figured out a way to get human eyes to review the words the computer couldn't read and tell them what the word says. Enter reCaptcha. –  JMC May 13 '11 at 13:44
    
@JMC I did not know that Google now owns reCaptcha. Last time I looked it was a Carnegie Mellon project. –  Treffynnon May 13 '11 at 13:50
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"Varying techniques" sounds like BS. How do you stop fake signups from bots? –  Eduardo Molteni May 13 '11 at 14:10
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2 Answers

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You have to look at Captcha as a security measure. With that in mind companies use Captcha for two reasons.

  1. It is the easiest and fastest solution for them to solve bot problems
  2. They are using other means of bot detection but they need additional layers and Captcha is one of those layers

As a company becomes bigger, more well known, and hosts more important/secure systems they become a bigger target. The level of security you need at your company is related to how big of a target you are, no security system is 100% foolproof. So when you see companies like Google, Yahoo, and eBay using Captcha don't be fooled into thinking that that is there only line of defense against bots. That is just one of their many barriers and they choose to use it because it is successful often enough and it is obvious enough that its existence will deter some hackers.

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Traffic filtering/limiting has to be done on the server and it's easier to add a captcha to a web page then set that up. Also, it's hard to get traffic filtering/limiting to spot a spambot which has the rate it hits a particular site set quite low.

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