When the Web began to develop at rocket speed at the end of the last century, so did spam. Spam quickly turned into a nightmare for many sites and webmasters desperately sought a solution to the spam problem. Such a solution was offered quickly and it was called CAPTCHA (Completely Automated Public Turing test to tell Computers and Humans Apart). The function of captchas was to stop spambots from doing their jobs.

As it turned out pretty soon, spambots (and their creators) aren't that stupid and they quickly figured out ways to outfox captchas. Nevertheless, captchas still manage to filter at least a portion of the spam a site is getting and this is why they are still in business.

However, this comes at a price. Captchas stop not only spambots but they are an obstacle to legit human visitors as well. What is worse, captchas stop only humans but search engine bots as well. If you have content that is accessible only after a captcha is entered correctly, it's quite obvious this content is out of reach for search engine spiders who even if they could, wouldn't bother with filling in captchas �?? they just move to the next site that is more welcoming.

In the worst case, the most annoying thing about captchas is that when they are not implemented properly, there is data loss. Consider the case when your captcha is next to illegible and/or when after the captchas is filled incorrectly, all the data on the form is wiped out and the mad user has to start from scratch. What do you think - how many of the users will bother to refill the form just to buy something from you, for example?

Captchas Hurt Conversions

Captchas are bad from usability point of view and as already mentioned, if they stop search engine spiders from indexing pages behind the captcha, they are bad for SEO as well. However, the real damage is done when you consider conversions. Captchas simply kill conversions and probably this is their worst disadvantage in terms of SEO.

Lost conversions matter more than spam. Spam might be irritating but it doesn't kill your business the way lack of conversions does. While the results vary from site to site, when captchas are on, this could decrease conversions big time. For instance, if you have a captcha on a newsletter signup form, this could cut your subscribers in half because many users won't even bother to try their luck with the captcha. If you have a captcha on a shopping site, this might spare you some fake orders but the number of frustrated customers will be times higher than this.

Basically, the more difficult and illegible the captcha, the higher the drop in conversions. If you don't believe it, experiment on your site with captchas with varying difficulty and take notes of the results.

Standard captchas that require the user to fill in letters and numbers are the most acceptable of all but they still are quite of a hurdle. Audio and video captchas are a real kill because they might require up to a minute of your users' time to listen to or watch and fill in. This is why it's hardly surprising that audio and video captchas are the ones with the highest give up rates.

Captcha Alternatives

Unfortunately, no matter how much technology advances, the real captcha alternatives are yet to be seen. This doesn't mean you are completely helpless against spam. Here are 3 captcha alternatives you might want to try:

Use a less annoying captcha variation. Out of the numerous captcha variations, there are some that are more acceptable to users, for instance the variation where a user has to solve a simple math problem (like 3+4) and enter the result. This captcha variety eliminates the illegible letters that piss users most and if you use simple math problems all your users can solve, this might solve the captcha problem for you.
Get Akismet, or other third-party anti-spam solutions. The next alternative you have is to use a dedicated anti-spam solution. The choice here is overwhelming and your options vary depending on what you need the spam filter for. One of the universal spam filters that is available for multiple platforms is Akismet, so if you haven't tried it so far, now is the time to do it.
Apply the honeypot technique. The honeypot technique includes a field that is to be left empty by the user. This way it is supposed that humans won't fill the field, only robots who don't understand the instructions will. However, the honeypot technique is everything but fool-proof. Absent-minded or visually impaired users could fill the field and smarter robots could avoid it. These are the reasons why the honeypot technique is not that popular in practice.

Time to Get Rid of the Captcha?

As you see, captchas are bad but their alternatives aren't much of a solution either. Therefore, the only option you might have is to get rid of the captcha. In many cases this could be your best move?? i.e. if you don't get huge volumes of spam but captchas kill your conversions, then you'd better part with it. On the other hand, if you do get huge volumes of spam and the captcha isn't that much of a problem for your users, the answer is obvious -? leave the captcha. You just need to analyze your situation in particular and decide what works in your case and what doesn't.