Simple lib to generate a math_captcha to prevent spammers in form. Supports localization.

Wrapper for Captchabot.com

API to interact with BrandCAPTCHA http://www.pontamedia.com/en/brandcaptcha/

A captcha that uses images instead of garbled text

Captcha based on encyrpting and decrypting user data by mathematical operation

Description of TinyCaptcha.

wxianfeng_simple_captcha is captcha for rails,modified from simple_captcha .

Antigate (Decode captcha service) wrapper for Ruby

A honeypot style captcha extension for ActiveRecord. Simple one-line inclusion in the model combined with a simple form field should trap the bad guys in the molasses.

It's a Rails Captcha Engine for Rails 3 applications.

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

Captcha form Jike API

Simple captcha image generator gem

Russian Post tracking toolset, consisting tracking form bot (since Russian Post is too retarded for normal API) and captcha solver/recognizer.

Implements view helpers for the ASIRRA CAPTCHA system for Rails-based websites

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

Anti-spam protection for your website

Helps humankind with simpler captchas

RedisCaptcha provides simple captcha that can be read by human.

MVC based Math, Logic Captcha