Install HTML-Tidy on CentOS

Installing HTML Tidy:

yum install libtidy

Add the module to your php.ini:
$EDITOR /usr/local/lib/php.ini

You’ll need to scroll down to the extensions area, I just keep searching for extension till I find it.
Add this line:
extension=tidy.so

Save, and restart your Apache web service:
service httpd restart

Test via phpinfo(); to make sure it’s working.