ALTCHA is a free, open-source CAPTCHA alternative that protects your website from spam and abuse

This gem enable to use Captchme. Anti spam, Monetize captcha and Audience qualification

SimpleCaptcha is available to be used with Rails 3 or above and also it provides the backward compatibility with previous versions of Rails.

create captcha for api based project

Block repetetive requests from logged_in users and shows captcha.

A gem to generate captcha pictures.

Google reCaptcha helpers and verifier

Integrate the AreYouAHuman.com CAPTCHA alternative human verification into your Ruby/Rails application

Captcha based on encyrpting and decrypting user data by mathematical operation

Merb plugin that provides resource access rate limits and captcha'ing

Simple negative captcha for Rails

dongsx

IQ, Math Captcha

A simple and fast image captcha generator that uses opencv and memcached.

Simple captcha

This is mt first gem

Anti-spam protection for your website

Simple captcha image generator gem

Solve Media CAPTCHA Replacement

Captcha generator for rails