The Joomla Tidy Plugin generates valid XHTML for your Joomla websites pages. It cleans the whole page, not just articles, so your Joomla website will always validate as XHTML1.0 per W3C standards.

It either uses the PHP Tidy Extension or Regular expressions if there is no PHP Tidy Extension installe.

Downloads

The PHP Tidy Plugin Joomla packages are made available in the downloads.

Source

You can also check-out the latest source from the repository.