About 16% of the world’s population lives with some form of disability yet many websites still fail basic accessibility checks.
Accessibility testing helps you find and fix those issues before they reach users. It checks whether websites and apps work for people with visual, hearing, motor, or cognitive impairments, and whether they meet standards like WCAG.
In this guide, you’ll learn what accessibility testing is, why it matters, and how to do it step by step. We’ll also look at the key accessibility standards, common issues to watch for, and the tools that can help you build more inclusive web applications.
What Is Accessibility Testing?
Accessibility testing is the process of checking whether a website or application can be used by people with disabilities. It helps identify barriers that make it difficult to navigate, understand content, or complete tasks using assistive technologies such as screen readers, keyboards, or voice controls.
In practice, accessibility testing checks things like whether images have descriptive alt text, whether every function is reachable by keyboard, whether color contrast meets minimum ratios, and whether screen readers can correctly interpret the interface.
To do this, most teams combine automated scans with manual testing. Automated tools quickly detect common accessibility issues, but they can’t tell whether an application is actually usable. The actual user experience needs to be tested by a human. Tasks like navigating with a keyboard, completing a checkout flow, or using a screen reader are usually tested by a person.
What Accessibility Standards Should You Follow?
Most accessibility testing is based on the Web Content Accessibility Guidelines (WCAG), developed by W3C. WCAG is the most widely accepted standard for making websites and applications accessible, and it’s the foundation for many accessibility laws and regulations around the world.
WCAG is built around four core principles, often referred to as POUR:
| Principle | What it means | Example |
| Perceivable | Users should be able to perceive all content, regardless of their abilities. | Providing alt text for images and captions for videos. |
| Operable | Users should be able to navigate and interact with the application using different input methods. | Supporting full keyboard navigation and visible focus indicators. |
| Understandable | Content and interface behavior should be clear, predictable, and easy to use. | Using consistent navigation, clear labels, and helpful form instructions. |
| Robust | Content should work reliably across browsers, devices, and assistive technologies. | Using semantic HTML and properly implemented ARIA attributes. |
WCAG also defines three levels of conformance:
| Conformance Level | Description | Target Recommendation |
| Level A | The minimum accessibility requirements that every website or application should meet. | Essential baseline. |
| Level AA | Addresses the most common accessibility barriers while remaining practical to implement. | Recommended target for most organizations and legal compliance. |
| Level AAA | The highest level of accessibility. | Optional; full compliance is not always achievable or practical for every product. |
For most websites and applications, WCAG 2.1 or WCAG 2.2 Level AA is the recommended compliance target.
Beyond WCAG, the specific standard you need to meet depends on where you operate and who you serve. Many countries have accessibility laws that align with WCAG. Depending on where your users are located, you may need to comply with one or more of the following:
| Region | Law or Standard | Applies to |
| United States | Americans with Disabilities Act (ADA) | Public-facing websites, applications, and digital services. |
| United States | Section 508 | Federal agencies and organizations working with the U.S. government. |
| European Union | European Accessibility Act (EAA) & Web Accessibility Directive | Public sector organizations and many commercial digital products sold in the EU. |
| United Kingdom | Equality Act 2010 | Organizations providing digital services to the public. |
| Canada (Ontario) | Accessibility for Ontarians with Disabilities Act (AODA) | Organizations operating in Ontario. |
| Australia | Disability Discrimination Act (DDA) | Businesses and organizations providing digital services. |
| India | Rights of Persons with Disabilities (RPwD) Act, 2016 | Government bodies and organizations providing accessible digital services. |
How to Perform Accessibility Testing (Step by Step)
Good accessibility testing combines automated scans, manual checks, and testing with assistive technologies. Here’s a practical workflow most teams follow:
1. Define Your Scope and Target Standard
Before running a single test, start by deciding what you’re testing and which accessibility standard you’ll measure against. This could be an entire application (although it’s not recommended), a specific feature, or a critical user journey such as sign-up or checkout. Most teams use WCAG 2.1 or 2.2 Level AA as their baseline.
2. Run Automated Tests First
Automated tools are the fastest way to surface common issues. Run axe DevTools, WAVE, or Lighthouse against your pages and collect the results.
Keep in mind that automated tools catch roughly 30 to 40% of real accessibility issues. They’re good at finding missing alt text, low color contrast, and missing form labels. They can’t tell you whether alt text actually describes an image accurately, or whether a keyboard flow makes logical sense.
Use automated testing to find obvious issues quickly; not as a sign-off.
3. Test Keyboard Navigation
Put the mouse away and navigate your product using only a keyboard. Here’s what to validate:
- Press Tab to move forward through interactive elements, Shift + Tab to move backward.
- Press Enter or Space to activate controls.
- Press Esc to close dialogs and menus.
- Every interactive element should be reachable with a visible focus indicator.
- Tab order should follow the logical page layout.
- Modals should trap focus inside until closed, and return focus to the trigger element after closing.
- No keyboard traps – users should never get stuck in a component they can’t exit.
4. Test With a Screen Reader
Screen readers are what users with visual impairments actually use. The most common ones are NVDA and JAWS on Windows, VoiceOver on Mac and iOS, and TalkBack on Android.
Navigate your product with a screen reader and check:
- Buttons have meaningful names, not just “click here” or “button”.
- Links describe where they go.
- Form fields describe their labels correctly.
- Error messages are clearly announced.
- Dynamic content updates such as alerts, notifications, cart updates are communicated to the user.
5. Check Color Contrast
Text needs a minimum contrast ratio of 4.5:1 against its background for normal text, and 3:1 for large text under WCAG 2.2 Level AA. Low contrast is the single most common failure in a large number of websites.
Check every text and background combination in your UI, including hover, focus, and disabled states.
6. Test Critical User Flows End to End
Don’t limit testing to static pages. Test the flows users actually depend on like login, signup, search, form submission, checkout, and payment. Verify that:
- Users can complete the full flow without a mouse.
- Errors are visible and announced to screen readers.
- Focus moves to the right place after each action.
- No custom widget blocks keyboard or screen reader navigation.
7. Test on Real Devices and Browsers
Accessibility behavior varies across browsers, operating systems, and devices. A focus issue that doesn’t appear in Chrome on desktop may show up on Safari on iOS. Test across Chrome, Safari, Firefox, and Edge – and on both desktop and mobile. Cloud testing platforms like TestMu AI let you run these checks across real devices without managing your own device lab.
8. Fix, Document, and Retest
Log every issue with its location, the WCAG criterion it violates, its severity, and steps to reproduce it. After fixes are applied, retest the affected areas. Accessibility regressions are very common – one code change can reintroduce a problem that was already resolved.
For ongoing coverage, integrate automated accessibility scans into your CI/CD pipeline so every pull request is checked before it merges.
What Are the Best Accessibility Testing Tools?
No single tool covers everything. Automated tools catch roughly 30 to 40% of real accessibility issues. The rest requires manual testing and screen readers. The right setup combines a few of these depending on what you need.
For automated testing, popular tools include axe DevTools, WAVE, Lighthouse, and browser accessibility inspectors. Screen readers such as NVDA, JAWS, VoiceOver, and TalkBack are equally important for checking how users with visual impairments experience your application.
If you’re testing across multiple browsers and devices, a cloud testing platform can simplify the process. TestMu AI (Formerly LambdaTest) lets you run accessibility checks on real browsers and devices without maintaining your own device lab. You can combine automated scans with manual validation to verify keyboard navigation, screen reader compatibility, color contrast, and other accessibility requirements across different environments.
The best results come from using these tools together rather than relying on any single one. Automated scans help you find common issues quickly, while manual testing confirms that real users can complete tasks successfully.
What Are the Best Practices for Accessibility Testing?
Beyond following a good testing workflow, a few simple practices can help you catch issues earlier and be more effective in your accessibility testing:
- Test early, not just before launch: Accessibility issues found late in development are expensive to fix. The earlier you catch them, the less rework is involved. Add automated accessibility checks to your CI/CD pipeline so every pull request is scanned before it merges.
- Don’t rely on automated tools alone: Automated tools are fast but limited. They catch missing alt text and low contrast reliably. They can’t tell you whether alt text is actually descriptive, whether a keyboard flow makes sense, or whether a screen reader user can complete a checkout. Manual testing fills that gap.
- Test with real assistive technology: Running a screen reader through your product tells you things no automated tool can. Use NVDA or JAWS on Windows and VoiceOver on Mac. Navigate using only the keyboard. Listen to what gets announced and whether it matches what a sighted user would see.
- Include real users with disabilities: Even a small number of sessions with users who rely on assistive technology will surface issues that no checklist would catch. This is the most reliable signal that your product is actually usable, not just technically compliant.
- Retest after every significant change: A code change that fixes one thing can break another. Accessibility regressions are common. Make retesting part of your release process, not a one-time audit.
- Document everything: Log issues with their location, the WCAG criterion they violate, severity, and steps to reproduce. This makes remediation trackable and gives developers the context they need to fix things correctly the first time.
Following these practices helps you build accessibility into your development process from early on. The result is a more inclusive product and fewer expensive issues to fix later.
Conclusion
Accessibility testing tools isn’t a one-time audit. It’s an ongoing part of how you build and ship software.
Start with automated tools to catch the obvious issues, layer in manual testing for what tools miss, and validate with real users when possible. The earlier this becomes part of your process, the less it costs to fix things and the more people can actually use what you build.
