Web Accessibility Validator

Criterion’s Web Accessibility Validator is an HTML validator which assists web developers in identifying Section 508 and WCAG accessibility failures.

Websites are written using markup languages such as HTML or XHTML. These languages are defined by technical specifications which include machine-readable formal grammar and vocabulary. The act of checking a website against these constraints is called “validation”.

Although HTML validation is helpful in identifying accessibility failures, HTML validation alone does not ensure Section 508 or WCAG compliance. In fact, HTML validation identifies less than 20% of basic website accessibility failures.

Despite these limitations, regularly scheduled HTML validation provides web development teams with a prioritized list of emerging accessibility failures that require immediate repair in order to maintain a websites Section 508 and WCAG compliance.

Questions? Call +1 (888) 508 EXPERTS for more information!

How does it Work?

A client’s website will be scanned on a monthly, quarterly or annual basis utilizing Section 508 guidelines and W3C WCAG 2.0 A/AA checkpoints. Violations identified will be documented in detail, including:

  • The nature of the violation
  • Its location in the website
  • “Before” and “After” suggestions for repair

Example of Web Accessibility Validator Report

Issue Found:
Field Element Labels:
Each form control should be explicitly associated with its label, or if that is not feasible, have a title attribute explaining its use. 131 violations of this issue were discovered amongst 30 pages.

Specific Issue: Each form field should be explicitly associated with its label or have a 'TITLE' attribute. Found 'no explicit Label provided and Title attribute is too short or missing' for field '<input> Tag type=text name='q''.

Suggested Remediation: Every form control must be associated with its label, and each control should have a label.

Screen sample of site showing a Textbox highlighted with exclamation point.
Go to top

Each issue flagged in the report will provide a ”Before“ and ”After“ HTML syntax example, saving web developer’s valuable time in maintaining compliance.


<form action="mailto:info@nrc.gov"> <label> Name <input type="text" name="Name" size=30> </label> <input type="text" name="Nickname" size=20><br> </form>

Note that the nickname field has no label, and the label wrapping the name field has no explicit connection to it. It’s important that the form field have an id attribute along with its name attribute; the for attribute of the label must match the value of the id attribute.


<form action="mailto:info@nrc.gov"> <label for="Name">Name</label> <input type="text" id="Name" name="Name" size=30> <label for="nickname">Nickname</label> <input type="text" id="nickname" name="nickname" size=20><br> </form>

Go to top