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

Helper for Turnstile Captcha API

Easy to use classical captcha for Rails apps

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

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

Solve Media CAPTCHA Replacement

A captcha that uses images instead of garbled text

This plugin adds helpers for the YinXiangMa CAPTCHA API

Quick little arithmetic plain-text captcha

A smart captcha library

To help with keep the bots at bay this gem helps you easily add honeypots to forms and/or obfuscate your form field names

LoyalSimpleCaptcha 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

Generates Text Catpchas, that are 'nice' by my own personal definition!

Simple negative captcha for Rails

My version of SimpleCaptcha

Repackaged visualCaptcha's backend service, including translation and minor modification. Mainly for private use. Everything still belongs to original author: emotionLoop. ...

Ruby port of VIT AutoCaptcha