There are plenty of good free browser features and installable add-ons available for accessibility checking purposes. Paid versions of checking tools provide more features that can be used. All of the tools and assistive programs listed on this page are provided free of charge, but some of them require registration.
The accessibility of websites can be assessed by carrying out a programmatic check by means of either an external service or a checking tool built into or installed onto a browser. However, programmatic checking tools are unable to correctly judge all aspects, so any ambiguous notifications must be verified with a manual check. One prerequisite for accessibility checking carried out by content producers is that they have access to appropriate applications.
All major browsers feature developer tools and features for checking accessibility. For example, Google Chrome and Mozilla Firefox have extensive and easy-to-use features.
Lighthouse auditing on Google Chrome
The Google Chrome browser features a built-in auditing tool provided by Google, which can be used for checking the accessibility of a page as well. After a check, the Lighthouse tool will give the page a numeric score between 0 and 100 and list:
- any accessibility shortcomings detected
- all tests passed
- any items to be checked separately
- any contents included in the check that the website lacks.
Axe is an accessibility checking tool created by Deque Systems. The tool will provide an account of the page’s accessibility and visually indicate the elements that the observations pertain to. This browser add-on must be installed separately.
The Axe check rules are listed and explained on the following website:
The NVDA screen reader is an open source program for the Microsoft Windows operating system. NVDA enables visually impaired people to use a computer with a Windows operating system without any additional costs arising from an assistive program. NVDA enables the user to perceive what is happening on the screen.
The WebAccessibility assessment tool can be used to assess accessibility and issues occurring on pages. Requires registration.
The Siteimprove add-on facilitates easy filtering of check results based on the user’s role. The available roles (areas of responsibility) are:
- content producer (editor)
- webmaster (duties requiring page content coding)
- developer (duties requiring the coding of global changes in a publishing system).
This enables content producers to print narrowed-down checklists. Some of the items assigned to be checked require understanding of code and technology.
Siteimprove enables the user to select the level of compliance (A, AA or AAA). The user can also select the issues to be reported based on their severity.
Other useful aids
Functional impairment simulation
It is often useful to have a mental image of how a functional impairment affects the way the person perceives the contents of a page. There are several different simulators for this purpose that can be used to examine how visual impairments affect the perception of contents.
One example is the NoCoffee add-on that can be used to illustrate many problems caused by impaired vision.
Checking the use and meaning of images
Images often play a significant role in the contents of pages. A good and easy way to check the alt texts of images and the functionality of the page without images is to use the ON/OFF add-on. This add-on makes it possible to hide all images with the press of a button, whereby the browser will display the page without images, replacing them with their alt texts.
Websites to help with checking
There are online services available for checking the accessibility of websites. Some of the checking sites offer auditing for a fee, while others will check the page similarly to the browser tools mentioned above. Checking tools installed into a browser are the easiest to use and always available to publishers.
Examples of websites for accessibility checking include the following:
The check carried out by the Siteimprove page only lists any issues detected but does not indicate where the issues are located, nor does it provide any detailed information about the technology of the page. Such a test result is not useful from an end user’s perspective. Instead, the Siteimprove browser extension works well and is recommendable.
There are also so-called one-aspect pages for checking the accessibility of a website, such as colour contrast checking pages. Examples of such pages include: