Limitations of Automated Web Accessibility Checkers

Automated accessibility checkers are a must in your Web Accessibility Auditing Toolkit, though it is important to understand their limitations. Think of an automated accessibility checker like a spell checker in a word processor. Though a good start for identifying misspelled words, a person must still read through the text to ensure words have been used correctly (e.g., where “there” is used in place of “their”). For now, human judgement must also be involved for any potential barriers that involve assessing meaning. For example, automated checkers can identify ambiguous phrases like “click here” or “this link” used as link text, but a person needs to determine whether this text accurately describes the link’s destination or function. Similarly, a person must decide whether alt text or a long description for an image accurately describes the meaningful information in the image, something automated checkers cannot currently do.

You may also want to make use of multiple accessibility checkers and compare results. See the Activity at the end of this unit for an exercise comparing automated accessibility checkers.

Another limitation worth noting is that automated checkers are unlikely to identify with certainty whether accessible equivalents are available for web content that has been flagged as a potential barrier. A human perspective is required to make the association between equivalent elements. However, the site provider may offer an accessible HTML version of the page as well. An automated checker would not recognize the connection between the barrier and its accessible alternative, but a person would.