In a form of an online service, reCAPTCHA offers exactly that. After signing up for the service, you’ll be able to place a captcha module on your website and avoid automated abuse while helping to read and store books of the past. With this special type of captcha engine, users are besides writing an already known word correctly into the widget’s field also required to recognize an additional word gathered by digitizing books which the OCR system wasn’t able to recognize due to various defects in characters.

Besides an obvious advantage of this service that makes real use of captcha, there are other great advantages to it. It’s easy to install thanks to plugin support for major CMS like WordPress, it’s accessible for eyesight-disabled people and it is based on high security standards that make it nearly impossible to penetrate. Moreover, the whole system can be quickly updated whenever a vulnerability is found without the webmaster having to worry about it. It’s also capable of IP filtering.

Should you wish for a great, free, customizable service with its own API that transforms waste of time into a useful and valuable activity while protecting your website against the dirt of spam? Here you go.