There is tidy for HTML. It’s more than a validator: it doesn’t only check if your HTML is valid, but also tries to fix it. But you can just look at the errors and warnings and ignore the fix if you want.
I’m not sure how well it works with HTML5, but take a look at Wanted: Command line HTML5 beautifier, there are some parameter suggestions.
For CSS there is CSSTidy (I have never used it though.)
Regarding the W3C validator: if you happen to use debian/ubuntu, the package w3c-markup-validator is in the repositories and very easy to install via package management. Packages for other distos are also available.
And the W3C CSS validator is available as a jar, which is easy to use:
java -jar css-validator.jar http://www.w3.org/.