Other than submit individual web pages for verification on the W3C site, are there any standalone tools that will do this job.
Ideally this would be a visual studio plugin that could catch errors at design time but one that would just take a wep application url running locally would be good.
Open source suggestions would be preferable
The W3C Markup Validator is an open source tool, which you can download and use it offline.
On Fedora, do:
yum install w3c-markup-validator