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 gem wrapper for tiny captcha in C with no dependencies.

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

ReCaptcha implements view helpers to generate ReCaptcha code, with the noscript counterpart, required methods that interface with the HTTP API for captcha verification, a DSL to generate a before_filter and the code to implement AJAX captcha validation.

SimpleCaptcha is the simplest and a robust captcha. Its implementation requires adding up a single line in views and in controllers/models. SimpleCaptcha is available to be used with Rails2.0 or above and also it provides the backward compatibility with previous versions of Rails.

A captcha verification approach for Rails apps, directly integrated into ActiveRecord’s validation mechanism and providing helpers for ActionController and ActionView.

这是一个验证码生成器。基于rucaptcha。本人只是将他的源码拉下来。为我的网站进行适配。因为我不使用sesion.id

A simple CAPTCHA implementation for Rails 5+ based on RMagick.

A Google-style captcha for enterprise Rails apps

A gem to generate captcha pictures.

Due to many unrequited complaints to the recaptcha team with regard to its unreadability for real human users, this gem offers a more readable selection of captcha images.

A Rails captcha gem that attempts to determine whether or not a user is human.

Metabypass | Ruby-based easy implementation for solving any type of captcha by Metabypass

Display and verify arcaptcha service captcha

A simple and custom captcha for Rails3.

Google reCaptcha helpers and verifier

AntiCaptcha api ruby wrapper

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

Arithmetic Captcha

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