Sanitize is a whitelist-based HTML sanitizer.  Given a list of 
acceptable elements and attributes, Sanitize will remove all
unacceptable HTML from a string.

Using a simple configuration syntax, you can tell Sanitize to
allow certain elements, certain attributes within those elements,
and even certain URL protocols within attributes that contain URLs.
Any HTML elements or attributes that you don't explicitly allow
will be removed.

WWW: https://github.com/rgrove/sanitize/