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Siteimprove HTML and CSS Validation

Sean Needham avatar

Note: This article refers to our old accessibility product. Information on our current next-generation Accessibility product can be found in Learn more about Accessibility NextGen

The Siteimprove Accessibility module gives details on HTML and CSS code that does not conform to W3C standards. In this article, we will explain how we conduct these checks and the benefits of complying.

Where do I find the Validation feature?

  1. Log into your Siteimprove account, choose "Accessibility" in the menu to your left.
  2. Click on "Validation".
  3. Click on either "HTML Validation" or "CSS Validation".


How do we validate your pages?

Validating your code to standards for HTML and CSS is like comparing a sentence with the rules of grammar for that language.

Using our website crawlers, we find HTML pages and run them through a version of the W3C Markup Validation Service. This service compares the HTML code on your web page to website standards. When your code does not comply with the standards we show the number of conformance errors next to each page and provide a link to the Markup Validation Service results.

The results page show where to change your code in order to become compliant. The Validation feature provides a complete list of all pages with validation issues, therefore removing the manual process of validating HTML page by page.

The validation feature checks your CSS code in a similar way and highlights any errors found. A green check-mark will be shown within the error column when the stylesheet has passed CSS validation checks.

Note: HTML validation is checked automatically every 30 days.

What are the benefits of complying with the W3C standards?

A central principle of the Web Content Accessibility Guidelines is robustness. This guideline aims to ensure that your web pages are built in accordance with web standards, providing the most reliable guarantee that future web platforms will handle your content as designed. Many accessibility issues are as a result of invalid code.

In addition to making a great start on accessibility conformance, here are some other benefits of having valid HTML and CSS:

  • Website Accessibility - Validating your HTML code helps pinpoint roadblocks that could prevent search engines or visitors from accessing your entire site.
  • Faster Loading - Removing unnecessary code can help create pages which help your website load faster. Faster loading provides a better customer experience and can help with search engine rankings.
  • Less load on servers - Clean code will not burden your server as much. This cuts down on the amount of Web space and bandwidth used, which can have a significant impact on cost.
  • Browser Compatibility - Validated code ensures your site is compatible with current web browsers, such as Chrome, Firefox, Safari and Internet Explorer.
  • Future-proof your work – Browsers are built with standards in mind. Pages coded to web standards today will work with browsers built tomorrow.
  • Makes maintenance easier – Standards are widely accepted by the development community. If your site uses valid code another developer should have no problem maintaining the site.

How do you update your results once improvements have been made?

Once validation improvements have been made on your web pages you can re-check specific pages using the check-box on the left along with the Re-check button. Otherwise, all pages are automatically validated every 30 days.

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