HTML::Tidy5 is an HTML checker in a handy dandy object.
HTML::Tidy5 does very little work. The real work of HTML::Tidy5 is done by the html-tidy library which is written in C. To use HTML::Tidy5, you must install html-tidy. Your package manager probably has it, either as "tidy" or "html-tidy" or "libtidy". If there's an option to get a "-devel" package, get that, too, because Perl needs the header files in it.
Once you have libtidy installed via one of the previous methods, install HTML::Tidy5 like any standard Perl module.
perl Makefile.PL make make test make install
COPYRIGHT AND LICENSE
Copyright (C) 2004-2018 by Andy Lester
This library is free software. It may be redistributed and modified under the Artistic License v2.0.