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Google’s Lighthouse Accessibility tool is built directly into Chrome and gives developers a quick way to check common accessibility issues alongside performance, SEO, and other website quality signals. When you run a Google Lighthouse Accessibility audit, it checks for common issues that can be detected automatically such as missing alternative text, insufficient color contrast, form controls without labels, and buttons without accessible names.
After the audit, Lighthouse produces an accessibility score out of 100. Getting a score of 100 is certainly a positive sign. But it does not prove that your website fully meets WCAG 2.1 or WCAG 2.2, satisfies every accessibility requirement, or provides an accessible experience for every user.
It also should not be treated as automatic proof of ADA accessibility compliance.
This is not limited to Google Lighthouse - it is also applicable for Deque’s Axe DevTools or WebAim’s Wave Accessibility Checker.
A website can pass every automated check and still contain barriers that only become apparent when someone actually tries to use it with a keyboard, screen reader, magnification software, or another assistive technology.
For example, a screen reader may fail to announce an important status message. An image may technically have alt text, but that text may not communicate anything meaningful. A modal may open correctly but send keyboard focus somewhere unexpected.
That is why automated testing tools like Lighthouse should only be a part of an accessibility testing process, not the entire process.
If Lighthouse identifies a problem, it is usually worth investigating immediately. Our guide to fixing common accessibility issues covers several of the barriers teams frequently encounter.
The limitation is that accessibility is highly dependent on context and user experience. A testing tool can often determine whether something exists. It cannot always determine whether that thing actually works well for the person using it.
Why a 100 Lighthouse Score Does Not Equal WCAG Compliance
WCAG 2.1 and WCAG 2.2 contain accessibility requirements covering a much wider range of user experiences than an automated tool can reliably evaluate.
As mentioned earlier, alt text of an image only serves its purpose if it describes the exact context that needs to be communicated to the user. The contents of a modal pop-up may be accessible, but there’s no use if the focus does not go into the pop-up area when displayed.
These problems can significantly affect usability while still being difficult or impossible for an automated accessibility test to fully understand. For organizations concerned about accessibility compliance, automated results should be supported by manual evaluation, assistive technology testing, and review of complete user experiences.
Accessibility is ultimately about whether people can understand the content, navigate the interface, interact with controls, recover from mistakes, and complete the tasks they came to perform.
Google Lighthouse Accessibility, Axe DevTools, and the WAVE accessibility checker may help teams get closer to that goal. They simply cannot replace the most important test: whether the website actually works for the people using it. And this can only be ensured with thorough manual testing effort.