Why a website accessibility checker doesn’t always ensure WCAG compliance

Two hands pointing to a laptop screen

by JP Corcoran

“Stop it at the start, it’s late for medicine to be prepared when disease has grown strong through long delays”

This 2,000 year-old adage from Roman poet Ovid may bear no relevance to the field of technology, but there is one underlying message that holds true; prevention is better than cure. Similarly, is it not better for a website to embrace best practices in universal design from the outset, rather than rely solely on automated tools that may fail to address the source of the problem?

What is a website accessibility checker?

A website accessibility checker is a tool that attempts to evaluate a website’s accessibility based on various accessibility guidelines and standards, such as the Web Content Accessibility Guidelines (WCAG) developed by the World Wide Web Consortium (W3C). Accessibility involves a wide range of disabilities, including visual, auditory, physical, speech, cognitive, language, learning, and neurological disabilities.

Such tools have a relatively short history, dating back to the late 1990s and early 2000s when the internet was becoming increasingly popular. During this time, web developers began to realise the importance of creating websites that were accessible to people with disabilities.

These accessibility checkers scan a website’s content and HTML code and provide feedback on potential accessibility barriers that may prevent users with disabilities from accessing and using the website. This may include issues with text alternatives for non-text content, keyboard accessibility, colour contrast, and more.

Other terms often associated with web accessibility checkers include web accessibility overlays and automated accessibility tools. Popular examples of such tools include accessiBe, Lighthouse, Deque axe, ReciteME, and WAVE.

Read more about Automated Tools – Lighthouse, Deque axe, WAVE & AccessiBe

Strengths and Limitations of Automated Tools

An automated tool that will check the accessibility of a website for you? Surely this can only be a good thing?

Website accessibility checkers can certainly be helpful in identifying accessibility issues and providing guidance for website developers and designers to improve the accessibility of their websites. However, there are also several limitations and potential drawbacks to consider. Let’s explore some of the pros and cons of website accessibility checkers.


Accessibility testing tools such the accessiBe and WAVE can help detect if a web page is inaccessible and identify issues that might otherwise be time consuming or difficult to identify manually. They will catch things such as missing Alt text, form controls without labels, and contrast errors. Automated testing tools excel when the decision logic can be boiled down to a simple yes or no answer, and that answer can be determined using machine accessible data. Automated tools can quickly locate a lot of obvious problems, reducing the initial time one needs to spend looking over a page for problems.


Passing automated accessibility testing however does not mean that a website or application is accessible. The greatest danger with automated accessibility tools is the assumption that they can somehow replace human involvement in improving accessibility. They are only one part of the toolkit. Sole reliance on them as sole indicators of accessibility compliance gives a false sense of security. In addition they may inaccurately portray a site or app as being fully accessible to people with disabilities when in fact problems exist. Evaluating website accessibility is an art not a science – it can’t be reduced to running a site through an automated tool. A level of human interaction will always be required to assure that content is fully accessible. An automated tool is not a complete solution.

Will automated accessibility tests ever replace actual accessibility testing?

While automated accessibility testing tools are a great option for checking large volumes of content quickly, they can’t replace the human eye when it comes to identifying nuanced issues with design and navigation. Manual accessibility testing is therefore still an essential part of any web development process.

Overall, website accessibility checkers can be a valuable tool in improving website accessibility, but they should be used in combination with manual testing and expert knowledge to ensure the best results.

This is why we need to treat automated accessibility tools such as accessiBe, Wave, and Lighthouse with a degree of caution and not a silver bullet for creating accessible websites. Taking this approach brings us closer to the ideals set out by Tim Berners-Lee, founder of the internet:

“The power of the web is in its universality. Access by everyone regardless of disability is an essential aspect.”