Anti-spam protection for your website

Simple captcha based on plain text questions.

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

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.

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

Merb plugin that provides resource access rate limits and captcha'ing

Gem that uses RuCaptcha API to solver any type of captcha

Helps humankind with simpler captchas

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.

This plugin adds helpers for the YinXiangMa CAPTCHA API

Description of RailsCaptcha.

Forked from https://github.com/kares/simple_captcha

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

This is a gem wrapper for tiny captcha in C with no dependencies.

Quick little arithmetic plain-text captcha

create captcha for api based project

MVC based Math, Logic Captcha

you will get arithmatic sum with answer you just have to compare with ur user in controller

NO LONGER MAINTAINED AND NOT RECOMMENDED, AS BOTS ARE ABLE TO RESOLVE CAPTCHAS BETTER THAN HUMANS. Based on Login Attempts check if captcha is necessary. It stores a permanent cookie and uses a table for tracking login requests.