We had trouble using the HTML5 with EPiServer CMS, it proved to be a bug.
The bug is that you have to write html 5 doctype in uppercase, ie <! DOCTYPEhtml>, to write doctype in lowercase makes EPiServer html parser removes thedoctype.
The actual bug is that the doctype should be case-insensitive - that you can see if you read the documentation for the doctype.
so use the <! DOCTYPE html> until the bug is resolved.
Woorank.com
Have used woorank.com a lot. It’s a pretty good tool to find out why a site or blog dont manage to get particularly high in search engine rankings.
It goes through site content and ranks it with their SEO algorithm, it also provides help with other types of information like visitors, in-site SEO, off-site SEO, usability and website information. It provides a basic SEO information for you to fix se basics of your site.
woorank.com