Open Directory - Computers: Internet: Abuse: CAPTCHA
See also: This category in other languages: - Open source system that uses spatial cognition abilities of humans to differentiate them from machines. - Includes demonstrations, research papers, and news. - PHP Captcha Script that generates unique captcha images to stop automated submissions, highly customizable, easy to install and configure. - A W3C Working Group Note explaining how CAPTCHAs can present a major obstacle to users who have limited vision or a learning disability such as dyslexia. This document examines a number of potential solutions and alternative systems. - An open source Java framework for captcha definition and site integration. Project information, documentation, issue tracker, and download. - Open source PHP script for generating image CAPTCHAs with audio alternatives. Includes documentation, a gallery and an online demonstration. [LGPL] - Offers a free and open source PHP script to reduce spam, also contains a detailed article about CAPTCHAs. - Explains how captcha features can keep spammers from signing up for certain accounts online, such as email or weblogs. Explains how the system can be circumvented as well. - A captcha system that uses successful decodings to helps digitise books for online use. Background, and details on how to incorporate into a site. Source code in several languages, and plugins for popular blogging and CMS software. - Paper by Rich Gossweiler, Maryam Kamvar, and Shumeet Baluja describing an investigation into a new type of CAPTCHA based on asking users to say which way up an image should be. [PDF] (April 01, 2009)
