Do you need a CAPTCHA? Or do you need to slow down / stop spammers? Consider hashcash [1] instead of CAPTCHA if #2 is your goal. It can be used in any place whe

Do you need a CAPTCHA? Or do you need to slow down / stop spammers? Consider hashcash [1] instead of CAPTCHA if #2 is your goal. It can be used in any place where real users interact with your site at almost zero effort on their behalf, and can slow down spamming enough to make you an unattractive target. I have a terrible / incomplete / janky proof-of-concept version at [2] that you could build from, or you could find one that was built for your CMS / language du jour. [1] https://en.wikipedia.org/wiki/Hashcash https://en.wikipedia.org/wiki/Hashcash [2] https://github.com/007/hashcash https://github.com/007/hashcash