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.

Anti Captcha is an automated CAPTCHA solving service

Simple gem to add captcha or negative captcha to your Rails 3 application

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

Tencent Cloud Ruby SDK is the official software development kit, which allows Ruby developers to write software that makes use of Tencent Cloud service CAPTCHA.

A captcha solver (only for easy ones) gem

reCAPTCHA was too much for us, so we created this. Simplest captcha ever.

SimpleCaptcha is available to be used with Rails 3 + 4 or above and also it provides the backward compatibility with previous versions of Rails.

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 Google-style captcha for enterprise Rails apps

A Google-style captcha for enterprise Rails apps

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

Simple captcha based on plain text questions.

A simple image captcha gem

Simple Audio Extension to Simple Captcha

MVC based Math, Logic Captcha

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

HumanDetector is a friendly logic captcha for Rails the doesn't require any external system dependency (e.g. external captcha API connections). It uses a simple question that any 7 or more years old human can understand, but that a spambot will not be able to answer. This Gem supports Ruby v1.9.2...

Captcha form Jike API

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