Authen::PluggableCaptcha is a fully modularized and extensible system for making Pluggable Catpcha (Completely Automated Public Turing Test to Tell Computers and Humans Apart) tests. Pluggable? All Captcha objects are instantiated and interfaced via the main module, and then manipulated to require various submodules as plug-ins. Authen::PluggableCaptcha borrows from the functionality in Apache::Session::Flex.