Simple negative captcha for Rails

Implementation of captcha (Completely Automated Public Turing-Test to Tell Computers and Humans Apart) that is both easy to use and easy to customize/extend.

Description of TinyCaptcha.

Antigate (Decode captcha service) wrapper for Ruby

Generates and verifies ascii art captcha.

dongsx

IQ, Math Captcha

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

Quick little arithmetic plain-text captcha

Forked from https://github.com/kares/simple_captcha

Description of RailsCaptcha.

Anti-spam protection for your website

Simple captcha image generator gem

Solve Media CAPTCHA Replacement

This plugin adds helpers for the YinXiangMa CAPTCHA API

Form protection with simple captcha calculations.

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

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.

Google reCaptcha helpers and verifier

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