I took at the link you provided, but it doesn't work without javascript

It seems to be intentionally damaged. Disable CSS too to see the page content without Javascript.

owasp.org fails at accessibility

Absolutely, and it seems to be intentional. The content is present, you just can't see it with CSS enabled, but Javascript disabled. It seems Javascript changes the CSS or the HTML to make the page readable again. That doesn't increase my trust in their product(s).

From the site:

ESAPI (The OWASP Enterprise Security API) is a free, open source, web application security control library that makes it easier for programmers to write lower-risk applications. The ESAPI libraries are designed to make it easier for programmers to retrofit security into existing applications. The ESAPI libraries also serve as a solid foundation for new development.

I read that as "sprinkle some magic fairy dust on your existing code and all security problems are magically gone". Smells like snake oil. Or maybe I'm just tired.

From the data sheet and the design patterns PDFs, it looks like a big fat form validator and a strange attempt to detect SQL injections. Several form validators are available on CPAN, not too hard to re-invent if needed, and SQL injection is impossible when you always use DBI placeholders.

So, what's left? Some buzzwords: Enterprise Security API, Web Application Firewall, design pattern.

Alexander