The best free accessibility checkers, ranked

A website accessibility checker is a tool that tests a page against the Web Content Accessibility Guidelines (WCAG) and reports the barriers it can detect automatically: missing alt text, low contrast, unlabeled form fields, broken heading order. Free checkers run as browser extensions or web services, and all of them check one page at a time.

In Germany the question became urgent on 28 June 2025, when the Barrierefreiheitsstärkungsgesetz (BFSG) took effect. It implements the European Accessibility Act and covers consumer-facing digital services such as online shops and booking flows. The technical yardstick behind it, EN 301 549, points to WCAG 2.1 level AA.

The baseline is poor. The 2026 WebAIM Million report found detectable WCAG failures on 95.9% of the top million home pages, 56.1 errors per page on average.

Tool	Runs as	Best at	Free tier
WAVE	Web service + extension	Visual overlay for non-developers	Fully free
axe DevTools	Browser extension	Precise rules, few false alarms	Free extension, paid Pro
Accessibility Insights	Browser extension	Guided manual testing	Free, open source
Lighthouse	Built into Chrome	A quick baseline score	Fully free
ARC Toolkit	Browser extension	Detailed rule explanations	Fully free

1. WAVE, the clearest view for non-developers

WAVE, from WebAIM at Utah State University, draws its findings directly onto the page: red icons for errors, yellow for alerts, green for features that work. Anyone can see where the problem sits without reading code. The web version checks public URLs; the browser extension also reaches staging sites and pages behind a login.

The overlay gets crowded on long pages, and “alerts” mix real problems with things that only need a human look.

2. axe DevTools, the developer standard

axe-core is the open source rule engine behind much of the accessibility tooling on the market, and the free axe DevTools extension is its most direct form. Its rules are tuned to avoid false positives: what axe reports is almost always a real defect, with the WCAG criterion and the failing element named.

Guided tests, full-page scans across a site, and CI integration sit in the paid Pro tier. For checking a page during development, the free extension is enough.

3. Accessibility Insights, the guided manual test

Microsoft’s Accessibility Insights for Web runs automated checks in its “FastPass” and then walks you through the manual part: tab order, focus visibility, landmarks, headings, all as a step-by-step assessment against WCAG 2.1 AA. It is free and open source.

It is the closest a free tool gets to a structured audit. It also takes the longest, which is the point.

4. Lighthouse, the score you already have

Lighthouse ships inside Chrome DevTools and runs a subset of the axe rules as part of its report. It is the fastest way to a number, and the number is the problem: a 100 means the automated subset passed, not that the page is accessible.

Use it as a smoke test in development. Do not use it as evidence.

5. ARC Toolkit, the explainer

TPGi’s ARC Toolkit adds a DevTools panel that lists errors and alerts with detailed explanations of each rule, which makes it a good teacher. It suits people who test by hand and want to understand why something fails.

What automated checkers cannot test

No tool on this list can certify compliance. Deque, the company behind axe, found in its own audits that automated rules caught about 57% of issues by count. The rest needs a person:

• Keyboard paths. Can every menu, dialog, and checkout step be reached and left with the keyboard alone?
• Meaning, not presence. A tool sees that an image has alt text. It cannot tell that “image123.jpg” describes nothing.
• Screen reader output. Whether a form error is announced, and in which order content is read.
• Flows, not pages. Every checker tests one page. Barriers often sit in the third step of a booking.

The errors checkers find most often

The WebAIM Million 2026 lists the same six failure types year after year. They cover most of what automated tests detect:

Failure	Share of home pages
Low contrast text	83.9%
Missing alt text on images	53.1%
Form fields without labels	51.0%
Empty links	46.3%
Empty buttons	30.6%
Missing document language	13.5%

All six are cheap to fix and most sit in templates, so one fix repairs every page. The same structure that helps screen readers also helps AI agents navigate a site; see what an agent-friendly website is and how AI assistants read German websites.

FAQ

What is the best free accessibility checker? WAVE for a fast visual check anyone can read, axe DevTools for precise results during development, Accessibility Insights for a guided manual test. Use at least one automated tool and one manual pass.

Can a free tool prove BFSG compliance? No. Automated tests cover a part of WCAG, and the BFSG also asks for an accessibility statement and a feedback channel. A clean report is a good start, not a conformity assessment.

Who has to comply with the BFSG? Businesses that offer covered products or consumer services, online shops among them. Micro-enterprises with fewer than 10 employees and at most €2 million annual turnover are exempt for services. This is not legal advice; check your case with a lawyer.

Which WCAG level is required? EN 301 549, the standard the BFSG refers to, maps web content to WCAG 2.1 level AA.

How often should I test? After every template or design change, and once a quarter for content. Most regressions arrive with a new banner, widget, or form.

We built our own free Barrierefreiheits-Check on the same axe-core engine: it renders your page in a real browser, runs the WCAG 2.1 A and AA rule set, sorts violations by impact, and groups them by WCAG principle, with a plain statement of what an automated test cannot cover. Full disclosure, it is ours, and it needs no signup. Accessibility issues often travel with privacy ones, so check the consent setup too in the best free cookie scanners, ranked. If the fixes sit in templates you would rather hand off, that is the work we do.