October 20, 2007

reCAPTCHA: Stop Spam. Read Books. Do Good.

Many sites use CAPTCHA mechanisms to secure comments and forums or access to certain features. Sadly necessary to prevent automated attacks and bot spamming, purportedly 60 million CAPTCHAS are solved daily. If we assume 10 seconds per, that represents 150,000 hours of human time wasted each day.

Carnegie Mellon's School of Computer Science realized they could reclaim that wasted time and put it to good use with reCAPTCHA, a free CAPTCHA web service that instead of presenting randomly selected letter/number sequences to solve, serves words from book scanning projects that failed OCR, thus lowering the cost of book digitization and preservation at the Internet Archive.

This is a brilliant leveraging of network effects for the common good.

reCAPTCHA addresses many usability concerns and meets Section 508 requirements by including an audio CAPTCHA for the visually impaired, the ability to refresh challenges if the current is too difficult to discern, and works when Javascript is absent or disabled.

I've implemented Josh Carter's reCAPTCHA plug-in for Movable Type -- take a look at the comments to see how it works. For this site I've chosen the 'blackglass' theme with some added CSS so that the input field uses my type style. You can also select from red and white themes, or elect to create your own styling on a 'clean' theme.

Visit reCAPTCHA's Resources page for info on the API, links to the many application and programming environment plugins and the reCAPTCHA developer community.

Posted by Lewis Francis at October 20, 2007 7:15 PM

If you are reading this in the IE8 beta, you may notice that reCAPTCHA's layout is busted. In an email response, reCAPTCHA stated they are tracking the issue and will provide a solution before IE8 ships.

Posted by: Lewis Francis at June 30, 2008 11:44 AM

As of IE8RC1, reCAPTCHA renders as expected.

Posted by: Lewis Francis at January 28, 2009 11:26 AM
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