require LWP::UserAgent;
require HTML::TreeBuilder;
my $ua = LWP::UserAgent->new(......);
my $response = $ua->get(......);
if ($response->is_success) {
    # get the document from the web
    my $r = $response->decoded_content;  # or whatever
    my $tidied_doc = HTML::TreeBuilder->new_from_content($r)->as_HTML();
..................
}
else {
    die $response->status_line;
}