Accessibility testing ensures your digital product is usable by everyone, including people with disabilities. To build accessible products, evaluate accessibility early and throughout the development process. This makes it easier to identify and fix issues. Different organizations promote different approaches for testing (e.g., Singapore's GovTech, UK's DWP), but most follow a similar workflow:
Fixing accessibility issues often requires rewriting code, following the correct order prevents duplicate work and saves time. Whenever you add or change your user interface, you should restart the testing process to ensure nothing has broken.
Automated testing offers a quick first pass at identifying accessibility issues. While these tools catch only parts of known problems, they efficiently detect obvious barriers. Note, however, as of 2025, automated accessibility testing tools work primarily for websites. Support for native desktop and mobile applications remains limited (this is actually a cutting-edge research topic). Below, we focus our discussion on automated testing for websites.
Before running accessibility tools, validate your HTML and fix any errors. Invalid HTML undermines accessibility regardless of other measures and breaks automated testing tools. Use a command-line tool like html-validator or the W3C Markup Validation Service for publicly accessible websites.
After validating HTML, use browser-based automated testing tools to identify accessibility issues. Popular options include Axe DevTools, Wave, and IBM Equal Access Toolkit. These tools work as browser extensions that you can install in Chrome, Firefox, or Edge.
To use these tools, open the website you want to test in your browser, then activate the extension. The tool will scan the page and generate a detailed accessibility report highlighting issues like missing alt text, color contrast problems, keyboard navigation barriers, and ARIA implementation errors. Most tools categorize issues by severity (critical, moderate, minor) and provide specific guidance on how to fix each problem.
While browser plugins require manual activation on each page, they offer several advantages: they provide graphical cues showing where issues occur on the page, they work on local development environments and password-protected sites, and they allow you to test interactive states like hover effects and form validation.
For developers comfortable with programming, integrating accessibility testing libraries directly into your codebase offers advantages. This approach enables you to automate accessibility checks as part of your continuous integration and deployment pipeline, catching issues before they reach production. You can run tests on every commit, validate accessibility across multiple pages simultaneously, and generate detailed reports for your development team.
Two widely-used libraries are axe-core and IBM Equal Access Toolkit. These libraries power the browser plugins mentioned earlier, but using them programmatically gives you greater control and flexibility. With axe-core, you can write automated tests that run against your application's pages and components, failing your build if critical issues are detected. The IBM Equal Access Toolkit offers similar capabilities. Both libraries provide comprehensive documentation and support testing against specific WCAG conformance levels (A, AA, or AAA).
Automated checking can reliably detect certain accessibility issues, including: