anti-captcha is a Ruby library for recognize captcha on anti-captcha.com

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

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

Captcha based on encyrpting and decrypting user data by mathematical operation

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

Captcha based on encyrpting and decrypting user data by mathematical operation

Submit captcha images and retrieve the text as a string.

Captchator as Rack middleware, and helpers for sinatra.

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

Captcha Gem for Rails, which generates captcha image by Rust.

Death by Captcha Ruby implementation (HTTP API)

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.

Generates and verifies ascii art captcha.

Simple negative captcha for Rails

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

generate captcha by dalli,use the memcache

Simple, easy captcha for Sinatra

Solve Media CAPTCHA Replacement

A captcha that uses images instead of garbled text