Death by Captcha Ruby implementation (HTTP API)

simple stupid captcha

It's a Rails Captcha Engine for Rails 3 applications.

A simple and custom captcha for Rails3.

RedisCaptcha provides simple captcha that can be read by human.

Rails mountable engine, that provides captcha support

Captcha Client for YunPian.com

Captcha form Jike API

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

Gem that uses RuCaptcha API to solver any type of captcha

A simple image captcha gem

generate captcha by dalli,use the memcache

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

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...

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

Simple, easy captcha for Sinatra

Simple captcha based on plain text questions.

DeathByCaptcha allows you to solve captchas with manual labor

BrainBuster - a logic captcha for Rails

Rack middleware Captcha verification using Recaptcha API.