HTML Validation (Slightly off topic)

How do you all go about validating your Lucee application to make sure that
all your pages produce valid HTML?

We currently use browser plugins but they only seem to work on a
page-by-page basis, so it’s easy to miss errors when testing a large

I can imagine a few possible solutions, such as a spidering validator, or a
proxy that validates, or even a browser plug that remembers history, but
have not been able to find any decent tools.

Any advice?