Yes, HTML-Tidy rules!

You might want to try (HTML-Kit) that is Freeware. And that has these modules: HTML-Tidy, HTML::Template and Perl-Tidy to edit your files.

It shouldn't be considered as Open Source but those sort of modules (done in their own JS like language) are maintained by a big community of users.

I cannot yet get used to editing all with it, but it might become very comfortable since you could test perl scripts, JS, HTML, create CSS, etc. It also has a sort of REGEX for massive file replacements.