Pylons (X)HTML Validator Middleware
This middleware will use the W3 Validator Service to check if your page is valid HTML. It will only check each URI once so that it doesn’t slow down your site by validating every page load. It does this by placing the result of each URI into a memory cache(using Beaker). You can then call cache_is_valid_xhtml() in your template to determine if the current page is valid. Note: The first time your page loads it will not display if the page is valid or not(It is validated AFTER the first response)....