Total Validator Rated 5 out of 5 stars
If you have more than a few pages in your site (15+) I highly recommend the pro desktop tool. I have been using it for about four years on a few smallish site (~100 pages), works GREAT! (OS: linux mostly fedora)
Thank you, yes, I do realize that I am supposed to be reviewing the firefox-add-on, on this particular page. However, a few years ago when I was quite skeptical about the desktop tool, I would have liked to see a review it.