The Quail Accessibility Information Library is an open-source, MIT-licensed suite of tests that assess web page structure and content. The library is currently developed against WCAG and 508, but additional guidelines may be mapped to tests using a tagging system.
Quail was started by Kevin Miller in 2009 as a PHP library specifically targeted at checking content accessibility within a CMS. Shortly after announcing Quail, he also developed the Accessible Content module for Drupal, which has been used in several government and higher education websites to give content authors feedback. On the train from Drupalcon Denver in March of 2012, Kevin re-wrote Quail as a jQuery plugin to help expand possible integrations to more projects. Quail continues to evolve through volunteer contribution and the leadership of Kevin.