Captchas and anti-spam Gems

#Total RankDaily RankNameSummary
1716881recaptchaHelpers for the reCAPTCHA API
22,4702,249voight_kampffVoight-Kampff detects bots, spiders, crawlers and replicants
32,9283,839rakismetRakismet is the easiest way to integrate Akismet or TypePad's AntiSpam into your Rails ...
44,8682,587invisible_captchaUnobtrusive, flexible and simple spam protection for Rails applications using honeypot ...