Site-Wide Validation

To validate HTML, CSS and/or Accessibility on a site, all you need to do is specify the starting URL. Here are the additional options that you can set.

New site validation form


To validate a site, you can define:

  • Starting URL. Our validation spider will visit this URL and its direct internal links, and validate those pages. Typically, you can enter the main URL of the site to validate, but it can be any URL from your site, or an XML sitemap.
  • Max. pages. The maximum number of pages to validate. There's a limit of 2,000 pages per each site validation, but you'll typically want to set a much lower limit.
  • Deep link scraping. By default, the validation spider will follow all internal links found, discovering more pages, until the max pages limit is reached or no more pages are found. This provides an easy way to submit a large site, but it's also slower than specifying exactly the URLs to validate with an XML sitemap.
  • HTML validation. If enabled, each page will be validated for HTML conformance.
  • CSS validation. If enabled, each page will be validated for CSS conformance. This will validate both inline styles and the linked stylesheets for each page.
  • Accessibility validation. If enabled, each page will be validated for Accessibility issues.

HTML Validation

We use the W3C Nu HTML Checker, hosted on our own servers, for HTML conformance checking.

CSS Validation

We use the W3C CSS Validation Service, hosted on our own servers, for CSS conformance checking.

Accessibility Validation

Site Validator lets you validate Accessibility on large sites by integrating with the leading tool in A11Y validation: Tenon.

Tenon integration

Tenon is the most complete A11Y checker, and currently implements 90 different checks. See What Tenon Tests for a comprehensive list of its current and planned checks.

Tenon is a paid service (see pricing) so to integrate it into your Site Validator account you'll need to register in order to get a Tenon API Key. When you've got one, you just need to enter it into your Site Validator account.

Tenon has a free tier but as it's limited to 50 checks per month you're encouraged to upgrade to a larger plan to be able to validate large sites.

Performance tips

Validating a large site can take a considerable amount of time, so in order to get your results sooner, consider:

Using an XML sitemap

You can provide an XML sitemap specifying the exact URLs to validate. If you do so, we won't need to crawl your site to discover the pages to validate, so we can start validating pages sooner.

You can read about the XML sitemaps protocol here, but in short, all you need is to specify each URL in this format:

<?xml version="1.0" encoding="UTF-8"?>
<urlset xmlns="">

You can generate this XML sitemap manually or by using a tool like this one.

Using XML sitemaps leads to much faster site validations, but also lets you be more organized when validating large sites. For example, you can use different XML sitemaps for the different sections in a large site.

By default, our validation spider will follow the initial URLs found from the starting URL, and discover additional pages until it reaches the indicated maximum pages to validate.

If you don't need us to discover additional pages, you can disable this option. For example, when you're submitting an XML sitemap with an exact set of pages to validate.

Validating a smaller set of pages

While it's tempting to try to validate sites in its entirety, in most cases that's unnecessary. For example, the New York Times site has over 33 million URLs, it would be impossible to validate the whole site. When you have a blog, or an online store, your site has easily thousands of pages, but most of them are using the same layout. Instead of validating each of them, consider building an XML sitemap with a sample of each different kind of page. You'll save credits and time.

Validate CSS separately

If you're validating CSS, most of the pages will be using the same stylesheets, so it's unnecessary to validate hundreds of pages for CSS. Consider validating just a small set of pages.

Also, you can check HTML, Accessibility and CSS separately. For example, if you have a 300-page site, you could validate HTML and Accessibility on 300 pages (or less), and CSS on 5 pages (or probably, just 1 page!).