How can I properly use website accessibility checkers?

There are several ways to test your website’s accessibility, including using website accessibility checkers. Depending on your goals, site complexity, and desired technical depth, different tools and methods can help identify, assess, and fix common accessibility issues.

How can I check if my website is accessible?

There are multiple ways to check a website’s accessibility. Ideally, you’ll make use of a combination of automated tools and manual testing methods.

To start with, you can use browser plugins or online website accessibility checkers to detect obvious issues. A common first step here is testing for colour contrast, alternative text for images, or checking the semantic HTML structure and form accessibility, using the <label> tag. However, many accessibility barriers go undetected by tools, such as unclear navigation or confusing language.

Manual testing helps fill this gap by having real users or accessibility experts using assistive technologies test the website. The results of all tests should be documented and prioritised in order to implement gradual improvements going forward.

What is the legal framework for accessibility in the UK?

In the United Kingdom, accessibility for digital content is governed primarily by:

• The Equality Act 2010, which applies to businesses, public services, and other organisations. The act mandates that websites must be accessible to people with disabilities, ensuring equal access to digital services.
• The Public Sector Bodies Accessibility Regulations 2018, which applies to public sector organisations, requiring them to make their websites and apps accessible to people with disabilities.

Additionally, the Web Content Accessibility Guidelines (WCAG) 2.1 serve as the de facto technical standard for achieving accessibility compliance, even though they are not directly codified into law for private businesses. Non-compliance can lead to legal challenges or investigations by the Equality and Human Rights Commission (EHRC), especially if a website creates barriers for users with disabilities.

Accessibility testing basics using automated vs manual tests

Before a website can be considered accessible, it needs to be tested across different usage scenarios. This requires both automated testing tools and manual testing - ideally used together. Each method has its own strengths and catches different types of accessibility barriers.

Automated testing

Automated tests are quick efficient checks using software tools like website accessibility checkers. They can detect issues like missing alternative text, poor colour contrast, or incorrect ARIA roles. These tools are particularly useful for initial accessible web design assessments and for ongoing quality assurance. However, when testing accessibility with these tools, you should keep in mind that they can only discover a certain percentage of potential barriers. Key problems such as ambiguous language, interactive functionality flaws, or unclear navigation structures often go unnoticed.

Manual testing

Manual testing fills the gaps left by automated testing methods through targeted usability testing and expert analysis. These manual testing procedures include operating the entire website using a keyboard, testing compatibility with screen readers, and assessing how clear and understandable the language and content are. This process actively incorporates the perspectives and experiences of users with motor, sensory, or cognitive impairments. Only through this complementary human evaluation can many barriers that automated tools miss be identified.

If you want to determine whether your website is truly accessible, implementing a structured testing process that combines both automated and manual methods is essential.

Top 5 website accessibility checkers

For an initial overview of a website’s accessibility, automated tools - also known as website accessibility checkers - are particularly suitable. Below is a selection of different options.

WAVE (Web Accessibility Evaluation Tools)

WAVE is a practical and free browser tool that allows you to quickly evaluate the accessibility of individual web pages. It highlights identified barriers directly within the page layout, immediately showing where improvements are needed. Additionally, WAVE offers specific guidance and recommendations on how to fix the issues it finds. The tool is particularly well-suited for beginners who want to get a quick overview of their site’s accessibility. In addition to the browser extension, WAVE also offers a paid API and a test engine that allows you to automate accessibility testing and integrate them into development processes.

axe DevTools (by Deque Systems)

axe DevTools is a powerful, developer-focused browser plugin that provides a free, precise, and detailed analysis of website accessibility. It detects a wide range of issues based on WCAG standards and provides specific guidance for fixing them, greatly simplifying the work involved. The plugin is suitable for both developers and QA teams looking to test accessibility efficiently. Deque Systems also offers additional paid solutions to test website accessibility. These enable seamless integration into common development environments, IDEs, and CI/CD pipelines, allowing accessibility testing to be automated as part of the development workflow.

Google Lighthouse

Google Lighthouse is an integrated testing tool in the Chrome browser, accessible directly via the Developer Tools. Among other features, it provides an Accessibility Score that gives a quick overview of a website’s accessibility, along with specific suggestions for improvement. Lighthouse tests include colour contrast, semantic HTML structures, and alternative texts for images. The tool also analyses other aspects such as performance, search engine optimisation (SEO), and best practices, making it particularly useful for comprehensive website optimisation. Since it runs directly in the browser, no additional installation is needed, which makes getting started easier.

Siteimprove Accessibility Checker

Like the tools mentioned above, the Siteimprove Accessibility Checker is a free browser plugin that checks the accessibility of web pages directly in the context of the current view. The tool visually highlights detected issues and classifies them according to WCAG criteria, severity, and affected user groups. Particularly helpful is the clear explanation of each issue and specific suggestions for fixes, making the tool accessible even to non-developers. Siteimprove emphasises practical relevance and user orientation, making it ideal for content editors and users with limited technical knowledge. The tool can also be integrated into the paid Siteimprove platform, allowing quality assurance, analytics and accessibility to be managed centrally.

Accessibility Insights

Accessibility Insights is a free tool developed by Microsoft, available as a browser extension for Chrome and Edge. It supports both quick spot checks and in-depth accessibility testing based on the WCAG guidelines. The tool offers two main functions: a FastPass for quick automated checks and an Assessment mode that allows for step-by-step manual testing. Particularly helpful is the visual highlighting of barriers directly on the page, along with a structured and well-documented guide to fixing issues. Accessibility Insights is specifically aimed at developers and is also available as a standalone app for Windows.

Manual testing and accessibility aids

Many problems that users encounter in everyday browsing can only be detected through manual testing. These include barriers related to content comprehension, structure, usability, or actual user experience. The following methods and tools provide practical ways to test a website from different perspectives.

Keyboard navigation

One essential manual test is to operate the website entirely using only the keyboard. This involves checking whether all content and functions can be accessed and used without a mouse. Typically, the Tab key is used to move between elements, arrow keys for navigation, and Enter or Spacebar to select items. This type of test is especially important for users with motor impairments or those who rely on keyboard-based input devices.

Screen reader tests

Screen readers are programs that convert screen content into speech or Braille output for blind or visually impaired users. Testing with common tools like NVDA (Windows) or VoiceOver (macOS) simulates this usage scenario. These tests can reveal issues with semantic structure, such as heading hierarchy, reading order, or missing labels on interactive elements. Learning to use screen readers takes time but provides valuable insights into the actual usability of a website.

Zoom and contrast checks

Accessibility isn’t at odds with modern web design trends - in fact, good design is accessible by default. Testing at increased zoom levels (e.g., 200%) and simulating colour vision deficiencies (e.g., grayscale mode) can help reveal design flaws and barriers for users with visual impairments. Common issues include poor colour contrast, content getting cut off, or interface elements that don’t scale properly. Most operating systems and browsers already include built-in features for running these checks quickly and easily.

Clarity of content

Accessibility is not just a technical issue. Website content must also be easy to understand. Text should be clearly structured, readable, and preferably written in plain language. Check whether technical terms are explained, sentences are concise, and paragraphs are logically organised. Artificial intelligence and language models LLMs can help evaluate how understandable your content is, or suggest simpler alternative wording. Interactive elements, such as forms or tools for scanning QR codes on a PC should also be designed for accessibility and tested accordingly. This benefits not only people with cognitive disabilities but also users with limited reading proficiency or non-native English speakers.

Checklists and WCAG criteria

The WCAG 2.1 define four key principles of digital accessibility: perceivability, operability, understandability, and robustness - often abbreviated as POUR. These principles form the foundation of many recognised testing procedures and checklists, such as the BITV test or the practical WCAG checklists provided by organisations like WAI or DIAS. Such structured testing tools help systematically identify accessibility barriers, prioritise necessary actions, and document progress in a transparent and traceable way.

What happens after testing?

After testing, the next step is documenting and analysing the results - ideally with clear priority ratings like ‘critical,’ ‘medium,’ or ‘low.’ Focus first on barriers that create major obstacles for users or have legal implications, like missing alternative text for images. These problems should be your top priority.

Long-term success means building accessibility principles into your design, development, and content creation processes. Think of accessibility as an ongoing responsibility rather than a one-time project. Here continuous improvement is key. It’s also a good idea to plan follow-up testing after major changes like website relaunches, technical updates, or new content additions to maintain the standards you’ve worked hard to achieve.

Conclusion

Testing website accessibility is not a one-time effort. It’s an ongoing process. By combining automated tools, manual testing methods, and well-structured checklists, you can identify and fix many accessibility barriers early on, before they become major issues. Accessibility goes beyond simply meeting legal requirements. Digital inclusion makes both ethical and business sense for today’s websites.

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