This package provides a pluggable mechanism for allowing users to
authenticate with your site.  It comes with a number of common plugins,
such as OpenID, BrowserID (a.k.a., Mozilla Persona), and email.  Other
packages are available from Hackage as well.  If you've written such an
add-on, please notify me so that it can be added to this description.

WWW: http://www.yesodweb.com/