This is part 2 of the Accessibility Testing series. All tools mentioned here are free — these are the ones I find most useful and use myself. They help catch accessibility issues automatically — in the browser, in your editor, and in CI.

Why use automated tools?

• Catch common issues fast — color contrast failures, missing alt text, invalid ARIA roles, broken label associations
• Check what’s hard to spot manually — contrast ratios, computed accessible names, ARIA attribute validity
• Establish a baseline — automated checks ensure basic standards are met before you start manual testing
• Prevent regressions — CI integration catches new issues before they reach production

Tools cannot check all accessibility aspects automatically. Human judgement is required. Sometimes evaluation tools can produce false or misleading results. Web accessibility evaluation tools can not determine accessibility, they can only assist in doing so.

— W3C WAI: Selecting Web Accessibility Evaluation Tools

To see just how far automated tools can miss the mark, read Manuel Matuzovic’s Building the most inaccessible site possible with a perfect Lighthouse score.

axe DevTools

axe DevTools is one of the most popular accessibility testing browser extensions. It scans the page and reports issues by severity (Critical, Serious, Moderate, Minor).

Install axe DevTools:

• Chrome
• Firefox
• Edge

How to use: Open DevTools, go to the “axe DevTools” tab, and click “Scan”. Review the issues list — each issue links to the affected element and explains how to fix it.

Lighthouse

Lighthouse is built into Chrome DevTools and uses axe-core under the hood for its accessibility audits.

• In the browser — DevTools → Lighthouse tab → check “Accessibility” → click “Analyze page load”
• CLI — npx lighthouse https://your-site.com --only-categories=accessibility
• CI — use Lighthouse CI to run audits on every pull request and fail the build if the score drops

Lighthouse gives you a score out of 100, but remember — a perfect score does not mean your site is accessible. It means the automated checks passed.

WAVE

WAVE is another excellent tool from WebAIM. It provides a visual overlay showing accessibility issues, structural elements, and ARIA information directly on the page.

Install WAVE:

• Chrome
• Firefox
• Edge

WAVE is particularly useful for its Structure view, which shows heading hierarchy and landmark regions at a glance.

CI integration with axe-core

The real power of automated testing is catching regressions before they ship. axe-core — the engine behind axe DevTools and Lighthouse — can be integrated directly into your test suite:

• @axe-core/playwright — run axe checks inside Playwright tests
• @axe-core/cli — run axe from the command line against any URL
• cypress-axe — run axe checks inside Cypress tests

This lets you fail a build when new automated-detectable issues are introduced. It won’t replace manual testing with keyboard and assistive technologies — but it prevents known issues from shipping unnoticed.

Other useful tools

WebAIM Contrast Checker

The WebAIM Contrast Checker is useful when you need to verify color contrast ratios against WCAG requirements:

• WCAG AA requires a contrast ratio of at least 4.5:1 for normal text and 3:1 for large text
• WCAG AAA requires at least 7:1 for normal text and 4.5:1 for large text

Browser DevTools

Both Chrome and Firefox have built-in accessibility tools — no extensions needed.

Chrome — Elements → Accessibility to inspect the accessibility tree, computed ARIA attributes, and accessible names.

Firefox — F12 → Accessibility tab. Firefox’s Accessibility Inspector highlights issues directly on the page and can check for keyboard/text label/contrast issues across the entire page at once.

For testing user preferences (reduced motion, forced colors, contrast, color blindness), see the Assistive Technology Testing post.

See also: Test keyboard navigation