The best accessibility checker depends on who'll use it: a free browser tool suits a quick check of one page, a content-author checker suits editors, and a monitoring platform suits teams with many sites. Eleven options follow in no particular order.
An accessibility checker scans a page for problems that stop disabled people using it: missing alt text, poor colour contrast, unlabelled form fields, headings out of order. It's a fast way to find the obvious issues before a customer runs into them.
The eleven tools below are listed alphabetically and in no particular order, from free open source tools to platforms that monitor thousands of pages. Every description comes from the vendor's own site, read this week. For the basics of what to fix and why, my guide to web accessibility is a good place to start.
Accessibility checkers at a glance
In the free plan column, Yes means the tool's own site names a free plan, a free version, a free tool or an open source edition. Trial only means a time-limited trial. Not stated means the pages I read named neither, even where there's a button inviting you to try it.
| Tool | Type | Good for | Free plan |
|---|---|---|---|
| Accessibility Insights | Accessibility testing tools from Microsoft | WCAG checks on websites and Windows apps | Yes |
| axe DevTools | Automated accessibility testing from Deque | Testing inside the developer workflow | Yes |
| Equalize Digital Accessibility Checker | WordPress accessibility plugin | Checking WordPress posts as you publish | Not stated |
| Level Access | Accessibility platform and services | Audits and VPATs for selling software | Not stated |
| Pa11y | Open source accessibility testing tools | Automated checks from the command line | Yes |
| Pope Tech | Accessibility monitoring platform | Monitoring many sites, such as universities | Yes |
| Sa11y | Accessibility checker for content authors | Helping editors fix issues as they write | Yes |
| Silktide | Website governance and accessibility platform | Checking pages and PDFs together | Not stated |
| Siteimprove | Web accessibility and content platform | Accessibility alongside SEO and analytics | Not stated |
| TPGi ARC | Accessibility monitoring platform | Catching issues introduced by releases | Not stated |
| WAVE | Web accessibility evaluation tools | Quick checks of a single page | Not stated |
Eleven accessibility checker tools to consider
Accessibility Insights
Best for: Developers who want free, open source tools to check websites for WCAG coverage and test Windows apps too.
axe DevTools
Best for: Development teams that want automated accessibility tests in their browser and pipeline, with free tools such as the browser extension.
Equalize Digital Accessibility Checker
Best for: WordPress site owners who want accessibility scans and reports inside the dashboard as content, themes and plugins change.
Level Access
Best for: Software companies that need audits and a VPAT to show buyers their product is accessible when contracts depend on it.
Pa11y
Best for: Developers who want free, open source command-line and dashboard tools to test pages automatically, including in CI.
Pope Tech
Best for: Universities and organisations with lots of sites that want WAVE-powered scanning across all of them, with a free plan.
Sa11y
Best for: Content editors who want a free, open source in-page checker that flags problems as they write, not a code audit.
Silktide
Best for: Organisations that want every page and PDF tested for accessibility, content and compliance, with a clear list of what to fix first.
Siteimprove
Best for: Larger marketing teams that want accessibility checks next to search, content and analytics reporting in one platform.
TPGi ARC
Best for: Digital teams that want continuous monitoring to catch accessibility issues introduced by releases and content updates early.
WAVE
Best for: Anyone who wants to paste in a web page address or use a browser extension and see accessibility issues marked on the page.
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Page checker, author tool or monitoring platform?
Single-page checkers are where to begin. You paste in an address or click a browser extension and see issues marked on the page. Author tools sit inside your editor or content system and flag problems while people write, which is where many issues start. Monitoring platforms crawl whole sites on a schedule and report trends, which suits organisations with lots of pages, PDFs and editors.
Developer tools are a fourth group. They run checks in the browser's developer panel or in the build pipeline, so problems are caught before code ships.
What W3C says checkers can't do
The W3C Web Accessibility Initiative, which publishes the WCAG standard, says evaluation tools can save time and help you avoid creating new barriers, but tools can't do it all. Some accessibility checks just cannot be automated and require manual intervention.
That's the most useful thing to know before you buy. A tool can tell you an image has no alt text. It can't tell you whether the alt text you wrote makes sense, or whether a keyboard user can get through your checkout. A clean scan is a starting point, not a certificate.
Questions to ask before you choose
- Do we need to check one page, or every page and PDF we publish?
- Who will fix the issues: developers, content editors or both?
- Does it work inside our content system, such as WordPress?
- Can it run in our build pipeline before changes go live?
- Does it explain each issue in plain language with a fix?
- Will we need reports to show customers or regulators?
Quick wins most scans uncover
- Images with no alt text. Describe what the image adds, or mark it decorative.
- Low contrast text. Light grey on white is a common culprit.
- Links that say click here. Name the destination instead.
- Skipped heading levels. Screen reader users navigate by headings.
Do you make accessibility checker tools? Tool makers can ask to be considered for a featured place on this list.
My plain advice on using an accessibility checker
Run a free checker on your five most visited pages today and fix what it finds. Then unplug your mouse and try to use the same pages with only a keyboard. Between those two tests you'll find most of the problems that matter.
Don't buy an overlay that promises to fix everything with one line of code. Fix the pages themselves, and use a checker to stop new problems creeping in. My piece on making your content accessible for everyone covers the writing habits that help.
Frequently asked questions
What does an accessibility checker do?
It scans a web page for common barriers, such as missing alt text, low colour contrast and unlabelled form fields, and shows you where they are.
Is there a free accessibility checker?
Yes. Several tools in the table name a free plan, a free tool or an open source edition. Check the free plan column for each one.
Can a checker make my site WCAG compliant?
No tool can do that alone. W3C says some checks can't be automated, so manual testing is always needed as well.
Which checker is best for WordPress?
A checker that runs inside WordPress, such as a plugin, lets editors see issues as they publish. One option in this list is built for that.
How often should I check my site?
Check after any design change and whenever you publish new templates. Larger sites benefit from scheduled monitoring.
What should I test manually?
Keyboard navigation, focus order, the meaning of alt text, form error messages and whether content still makes sense when zoomed in.
