I made this java app (Windows installer) in my spare time because I needed it at work:
https://gsoft.no/validator. It's free.
It uses either https://validator.w3.org/ or v.Nu running locally to validate an entire site.
It crawls a website and in the end makes a report with validator-links to all pages with warnings or errors. Because it crawls, all pages to be validated must be linked.
By running v.Nu locally you can validate an internal site (e.g. an intranet) which is not available online and therefore cannot be validated by online validators (unless you post the entire content of each page).
