HTML-Strip-Whitespace
CPAN Record
http://metacpan.org/release/HTML-Strip-Whitespace
Description
This is a module to strip whitespace out of HTML pages. As opposed to other solutions (like HTML-Clean), it does not touch whitespace inside <pre> tags (and in the future possibly other whitespace-aware markup.)
Using the HTML-Tidy (or otherwise the HTML Tidy library) for that may be preferable, because they are probably faster, but this module still exists and will be maintained.