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11 July 2019

It’s a
common story – you’ve been asked to check if your website is accessible, so you
figure the best place to start is to look up this ‘WCAG’ thing everyone’s
talking about. Upon arriving on the page of the latest Web Content Accessibility Guidelines
, you send it off to the printer figuring that you can use your spare
10 minutes later in the day to find the answer. After a short pause you head to
the printer to pick up the document only to discover its out of paper, the toner
is low and an entire ream of paper has been used up with the printer wanting
more. It’s at this point you realise checking webpages for accessibity is not going
to be easy.

there’s a number of free tools that can help you to sift through the complexities
of the WCAG standard, providing the ability to check your web content against
many of the testable success criteria and present the information in an
easer-to understand manner. In this article I’ve highlighted a selection of free
tools that I’ve found useful, along with some recommendations that keep being discussed
in the Professional
Certificate in Web Accessibility
course that I teach.


you start using automated web accessibility testing tools, there’s a few things
you will need to know about how they work and their reliability. Firstly, most online
tools work by providing you with a box whereby you can enter a web address.
After selecting ‘submit’ or an equivalent option, you’ll get a webpage back
that explains how accessible your chosen webpage is. If you are using a tool inside
a web browser such as a Chrome extension, the tool works by installing the
extension, visiting the webpage, then selecting the options in the extension to
do the same type of test. The results will then be displayed and explained in
relation to the WCAG standard, highlighting why the webpage is or is not
compliant. Most free tools tend to only check one webpage at a time with more
advanced features being left to the commercial products.


While the
testing process is straightforward, there’s several things you need to consider
when it comes to interpreting the results. Here’s some important points to

  • Automated tools cannot check all aspects of WCAG: it is important to note that even the best tools can only check about half or less of the current WCAG standard. As such, there is still a lot to be tested. Read through the documentation of the tool you’re using to find out what it can and can’t do in relation to its testing processes.
  • Beware false results: most tools use JavaScript or other coding platforms to assess the content. So what happens when it runs into similar code during the testing process? Inaccurate results with sometimes entire sections of a webpage not tested correctly.  This can often lead to both false positives and false negatives, so consider the results with a little scepticism.
  • Different tools give different results: if you use a free automated tool to check itself (e.g. enter the WAVE web address into the WAVE checker) you’ll find that it says the web page is completely accessible. However, if you enter the WAVE web address into a different automated tool, you’ll find it reports there’s errors. This is largely due to the coding methods used to check a website as mentioned in the previous point, so it may be helpful to consider the results of several tools to identify if an issue is there.
  • Automated testing does not replace user testing: while automated tools can be useful, they cannot replace the actual use of people with a disability testing the content with assistive technologies or the testing of every WCAG success criteria in a formalised audit process. If you simply run an automated tool over a webpage and fix those errors it’s unlikely that the web content will be accessible.
  • Many tools need updating: while most tools support the WCAG 2.0 standard, few have been updated to the WCAG 2.1 standard meaning that there are a number of important success criteria that will be missing from your tests if you are aiming to conform to the latest WCAG 2.1 standard.


Based on the issues above, you may be asking whether its worth using such tools at all given the risks. In my opinion, it is worth using automated tools. In specific circumstances, such as locating missing alternative text, they can be very useful as they will clearly highlight where the issue is and guide you to the correct location to make the change. This can save a lot of time and effort in hunting around the code trying to track down a potential issue. That said, it’s important to ensure that testing with assistive technologies and methodical testing against all aspects of the WCAG standard that you’re testing against is the priority. If it is, these tools can be very useful.

demonstrate the tools in action, I’ve used where possible an archived version of
Mr Bottles, one of the most inaccessible websites I’ve ever come across. However,
some of the online tools couldn’t recognise the URL so in these instances I’ve
just used Google which is a very simple and accessible webpage.  



WAVE Online screenshot

If you’re in a working environment where the Standard Operating Environment (SOE) on your workstation is locked down like a fortress, you may not be able to install some of the popular browser extensions or automated tool software. In these instances, there’s two online tools I’d recommend. The first is WAVE.

The benefit
of the WAVE tool is that it provides the results in an intuitive and visual
manner which can be helpful to easily identify issues such as alternative text
and colour contrast.


aChecker Online Screenshot

The other
online free tool that I really like is aChecker. This tool is not as
visually appealing as WAVE, but can make it easier to hunt down issues through
its comprehensive reporting structure.

There are
many other free online tools available but in my view using WAVE and aChecker
together provide you with a good overview of the issues, presented in different
styles and can be useful in cross-checking the validity of results.


WAVE for

WAVE Chrome extension screenshot

Similar to the WAVE online tool, the WAVE Chrome extension is very popular among web accessibility specialists. Once the extension is installed in the Chrome Browser, it is a relatively straightforward process to browse to the webpage you’d like to test, then using the extension to test it, providing a useful report.

Axe for Chrome

Axe Chrome extension screenshot

A second
tool to consider is Axe,
 This tool is more difficult to use, as
the extension requires some digging through the developer settings to bring up.
Its output is also more technical focusing heavily on addressing coding issues.
While not as easy for new users, technical professionals will find its attention
to detail very useful in hunting down accessibity issues.

toolkit for Chrome

ARC toolkit for Chrome Extension screenshot

works a little bit like Axe in that you must wade into the developer
settings to find it, but it also performs a comprehensive analysis on all web

accessibility checker for Chrome

SightImprove Chrome extension screenshot

The last of the four tools I’d recommend is the SiteImprove accessibility checker which is a little more intuitive in its design and provides some useful results.

Mozilla Firefox
 Accessibility Inspector

It’s also worth noting that the latest version of Mozilla Firefox also has a built in automated accessibility tool. If you are a Firefox user, you can enable the Accessibility Inspector to check your content.  

These are just a small portion of tools available. If you’d like a more comprehensive list of both free and commercial tools, the W3C has a list of accessiblity tools to consider. If there’s a tool you like to use that’s not on the list, let me know by e-mail or Twitter and I’ll look to add it to the list.

The Centre for Accessibility is a joint project by Media on Mars, DADAA and Dr Scott Hollier and is funded by the Department of Communities, Disability Services.

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