RedisCaptcha provides simple captcha that can be read by human.

Anti-spam protection for your website

Wrapper for Captchabot.com

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

A simple image captcha gem

ZeroCaptcha allows companies to solve captchas with artificial intelligence software, which is faster than humans and very accurate

Simple negative captcha for Rails

Ruby package for easy integration with the API of 2captcha captcha solving service to bypass recaptcha, hcaptcha, funcaptcha, geetest and solve any other captchas.

Description of RailsCaptcha.

This version include two important page 'Contact' and 'Register' with the 'Math-Captcha' method submit for prevent hacker attack.

Ruby port of VIT AutoCaptcha

A gem to generate captcha pictures.

Unity Captcha is a gem that use two levels of Captcha. First level is about Left Hemisphere: Logic and Math. Second level is about Right Hemisphere: Intuition and Drawing. This two levels functioning in complete harmony creates unity and this is the base design of this Captcha.

This is a Captcha gem for Rails Applications. It drawing captcha image with C code so it no dependencies.

This library can help you create a captcha in your terminal application, which may be damaged by a large influx of requests.

you will get arithmatic sum with answer you just have to compare with ur user in controller

Captcha Client for YunPian.com

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

This is a gem wrapper for tiny captcha in C with no dependencies.

Display and verify arcaptcha service captcha