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Free vs paid accessibility scanners: what you get

What a free accessibility scanner checks, what paid tools add, and where both stop: single pages vs full journeys, standards mapping, honest coverage.

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Pavel Charkasau

A free accessibility scanner is worth running, and you should run one today. A browser extension like axe DevTools or WAVE, or the Lighthouse audit built into Chrome, will check a single page against a large slice of WCAG in a few seconds, at no cost. That catches real problems: a missing text alternative, a form field with no label, contrast that falls below the ratio. What you pay for is not a longer list of rules. It's scope and evidence: scanning a whole site including the pages behind a login, tying each finding to the standard you're actually held to like EN 301 549 or the ADA, keeping a history so a re-scan shows what you fixed, and turning results into paperwork an auditor will accept. Both kinds of tool stop at the same wall. Automation catches somewhere between about 30% and 57% of issues; the rest needs a person with a keyboard and a screen reader (Deque). Neither a free nor a paid scanner makes your site compliant on its own.

What does a free accessibility scanner actually check?

A free scanner checks the rules a machine can decide on its own, on the page you point it at. That's a genuinely useful set. It reads the rendered HTML and flags things with a clear right-or-wrong answer: an <img> with no alt, a button whose only label is an icon, an input with no associated <label>, text whose contrast falls under 4.5:1, a heading level that skips from h2 to h4. Each of those maps to a WCAG success criterion, and the good free tools tell you which one. A finding that reads "image has no text alternative — 1.1.1" with the element and CSS selector is something a developer can fix before lunch.

The W3C keeps a filterable list of these tools, and you can narrow it to free and open-source ones. Its guidance is worth reading before you pick one: it separates tools by which technologies they check (HTML, WAI-ARIA, PDF), and notes that "some tools check a single page, while others check entire groups of related pages" (W3C WAI). Most free tools sit firmly in the single-page column. That's the first line worth understanding.

Where do free scanners stop?

Free tools stop at the edge of the page you're looking at, and at the login screen. Two limits matter most.

The first is scope. A browser extension checks the one page open in your tab. To cover a site you'd open every page by hand and run it again each time, which nobody does past the first few. So the marketing homepage gets tested and the fifty template-generated product pages don't. The W3C draws the same line and adds the one that bites hardest: whether a tool can reach "password-restricted content" at all (W3C WAI). Most free tools can't. The dashboard, the multi-step checkout, the onboarding wizard, the account settings, all the places where real barriers cluster, sit behind a login the extension never crosses.

The second is memory. A free scan is a snapshot. Close the tab and it's gone. There's no saved history, so you can't prove to a client or an auditor that the contrast error they flagged in March is fixed in August. You re-run it and eyeball a fresh unrelated list. For a one-page personal site that's fine. For anything you have to stand behind, the lack of a record is the problem, not the rule coverage.

What do you actually pay for?

You pay for coverage of the whole product, and for output that survives without you in the room. Five things, roughly in order of what they're worth.

  • Full-site and authenticated scans. A crawler that walks the site, plus scans that run signed in or follow a scripted journey from product page to confirmed order. That single logged-in run usually finds more than the entire public site. You can try a free scan on one page first to see the shape of the output before you commit.
  • Standards mapping, not a vanity score. A number out of 100 is not something you can defend in procurement. Paid tools worth the money tie each finding to a named criterion, so you can hand someone the WCAG checklist and show which rows the scan covered and which still need a manual pass.
  • History and re-scans. Findings attached to a saved site, so a re-scan shows the delta after a fix and a scheduled run catches a page that drifts back out of conformance in June.
  • Evidence and paperwork. Under the EAA you have to publish an accessibility statement that documents your real conformance level, known gaps, and a feedback contact. A tool that drafts an honest one from your actual results, through something like an accessibility statement generator, saves the hand-writing and keeps the claim truthful.
  • Team and pipeline features. Seats for the people doing the work, a check that runs in CI so a regression fails the build, issue sync into the tracker your developers already use.

None of that is a different rule engine. It's the same automated checks, wrapped in scope, records, and workflow. So the honest line between free and paid isn't about who finds more bugs on a single page. Paid earns its cost by covering the pages a free tool can't reach and keeping the proof a free tool throws away.

Does a free or paid scanner make you compliant?

No. Neither does, and any tool that says otherwise is the one to walk away from. This is the part both free and paid vendors are tempted to blur, so it's worth stating flatly. Automated testing catches part of the problem. Deque's study of more than 2,000 audits across 13,000 pages and nearly 300,000 issues put the ceiling near 57% by volume, above the older 20–30% figure based on how many success criteria a tool can even evaluate (Deque). WebAIM says it without hedging: "No automated evaluation tool can tell you if your site is accessible, or even compliant" (WebAIM). The W3C puts the same limit in one line: tools "can not determine accessibility, they can only assist in doing so" (W3C WAI). What's left over is the human half: a keyboard trap, a focus order that jumps around the page, a screen reader that announces "button button", a form error only a sighted mouse user would ever notice was missing.

Here's the one opinion I'll put my name to. Price has nothing to do with honesty here. A free extension that reports "12 issues" and a paid platform that reports "score: 88" are both fine, as long as neither dresses the number up as compliance. The tool to avoid, at any price, is the one that promises to finish the job for you. The US Federal Trade Commission made that concrete on 22 April 2025, ordering the overlay vendor accessiBe to pay $1 million and barring it from claiming its automated product "can make any website WCAG-compliant" — the FTC called that claim false and unsubstantiated (FTC). A million-dollar order is a clear signal about what a scanner can honestly promise. Use one, free or paid, that tells you where it stops.

Which should you use, and when?

Start free, upgrade when the stakes or the scope grow. A rough guide:

  • A free scanner is enough when you own one small site, you're spot-checking a single page you just changed, or you're learning what the errors even mean. Run axe, WAVE, or Lighthouse on the page and fix what it flags.
  • A paid scanner earns its cost when you have an application behind a login, a checkout to protect, more than a handful of pages, a client or auditor asking for evidence, or a legal deadline under the EAA, the ADA, or Section 508. At that point the free tool's blind spots (logged-in flows, no history, no standards report) are exactly the parts that matter.

Whichever you pick, budget for the manual half. A scan of any kind is the first pass, not the audit. Run the automated tool to clear the easy findings fast, then have someone drive the key journeys with a keyboard and a screen reader for the rest. That's the honest workflow, and it's the same shape whether the scanner cost you nothing or a subscription.

Frequently asked questions

Is a free accessibility scanner good enough for a small business?

For a genuinely small, single-page or brochure site, a free scanner plus a manual keyboard-and-screen-reader pass can be enough. Once you have logged-in flows, a checkout, or a legal deadline to document, the free tool's lack of scope and saved evidence becomes the gap.

What's the real difference between free and paid accessibility scanners?

Rule coverage is broadly similar; the difference is scope and evidence. Paid tools scan whole sites including pages behind a login, keep a history so re-scans show progress, map findings to standards like EN 301 549, and produce reports and statements you can hand to an auditor.

Can any accessibility scanner make my website compliant?

No. Automated testing catches roughly 30–57% of issues; the rest needs human review. The FTC fined accessiBe $1 million in 2025 for claiming its automated tool could make sites WCAG-compliant. Treat any "makes you compliant" claim, free or paid, as a red flag.

Do free scanners check pages behind a login?

Usually not. Most free browser extensions and single-page checkers only test the page currently open and can't reach password-restricted content, which is where many real barriers live. Authenticated scanning is one of the main reasons to move to a paid tool.

Which free accessibility tools are worth using?

Browser-based tools like axe DevTools, WAVE, and Chrome's built-in Lighthouse are solid free options for single-page checks. The W3C keeps a filterable list of evaluation tools you can narrow to free and open-source ones.

Try it on a real page

The fastest way to see the free-versus-paid line for yourself is to scan a page that matters. Run a free scan on your checkout or your logged-in dashboard, read the findings mapped to WCAG, and decide from there whether you need the scope and evidence a paid plan adds. No overlay, no badge, no promise it's finished.

Written by Pavel Charkasau, founder of wcagc.com. Last updated 9 August 2026.

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