A smart captcha library

A very simple rack captcha middleware via captchator.com API

jQuery slide captcha system with jQuery & jQuery UI for Rails 3

Submit captcha images and retrieve the text as a string.

Captchator as Rack middleware, and helpers for sinatra.

Arithmetic Captcha

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

Define questions and answers in a YAML file and validate your models with a single line of code. No more captchas or other stupid tricks.

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

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 and Rails 3.0.x.

Simple reverse captcha solution that consist in create a hidden field that should be always empty.

Rack middleware Captcha verification using Recaptcha API.

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.

Simple negative captcha for Rails

A Google-style captcha for enterprise Rails apps

Quick little arithmetic plain-text captcha

Simple negative captcha for Rails

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

Simple, easy captcha for Sinatra

A Google-style captcha for enterprise Rails apps