Website Accessibility Checker: HTML Pre-check

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Screen server-returned HTML for selected accessibility markup issues before browser testing. This cannot test contrast, keyboard behavior, focus, dynamic states, or WCAG conformance.

How the Website Accessibility Checker Works

This tool parses a page's server-returned HTML for selected patterns related to accessibility:

  1. Enter a URL, the tool fetches the page HTML and analyzes the markup for accessibility issues.
  2. Markup checks, it looks for selected patterns related to WCAG success criteria and labels separate best-practice findings.
  3. Issue categorization, each issue is tagged with its WCAG criterion number, severity (error/warning/info), and POUR principle.
  4. POUR principle breakdown, see how many issues fall under each WCAG principle for a structured view of your accessibility posture.
  5. Detected patterns, it also lists markup patterns found in the response; these are not proof of conformance.

Why Web Accessibility Matters

Accessibility isn't optional, it's a legal requirement and a competitive advantage:

  • Accessibility responsibilities, applicable duties depend on jurisdiction, service and organization. The European Accessibility Act covers specified products and services and includes exemptions. An HTML pre-check cannot establish legal compliance.
  • Audience reach, 16% of the world's population lives with a disability. Inaccessible websites exclude potential customers and users.
  • SEO benefits, many accessibility practices directly improve SEO: alt text, heading structure, semantic HTML, page titles, and proper link text are ranking signals.
  • User experience, accessible design benefits everyone: captions help in noisy environments, keyboard navigation helps power users, clear structure helps all readers.
  • AI search, AI engines parse semantic HTML and ARIA landmarks to understand content structure. Accessible sites are more extractable for GEO.

Pair this with the Image SEO Checker, Heading Checker, and Meta Tag Checker for a broader markup review. The Color Contrast Checker calculates selected foreground/background ratios, but a rendered-page audit is still needed. Also check mobile-friendliness, many accessibility issues (small tap targets, no viewport meta) directly overlap with mobile usability problems.

The Four WCAG Principles (POUR)

WCAG organizes accessibility requirements under four principles:

  • Perceivable, content must be presentable in ways users can perceive. This covers alt text for images, captions for video, sufficient color contrast, and text alternatives.
  • Operable, interface must be operable by everyone. This covers keyboard navigation, skip links, page titles, sufficient time limits, and avoiding seizure-inducing content.
  • Understandable, content and interface must be understandable. This covers language declarations, consistent navigation, form labels, and error handling.
  • Robust, content must work with current and future technologies. This covers valid HTML, proper ARIA usage, and compatible markup.

For deeper technical SEO fixes, check your schema markup, security headers, and overall SEO.

Next steps

Website Accessibility Checker related tools and articles

Continue with the closest follow-up checks and guides based on this tool's topic, crawl intent, and optimization workflow.

Image SEO: Alt Tags, File Names, Formats and Compression

Website Typography Guide: Font Sizes, Hierarchy & Best Practices

Best Fonts for Websites: How to Choose (2026)

Image SEO & Alt Text Checker

SERP Preview Simulator

Color Contrast Checker

Website Accessibility Checker: FAQ

What does this accessibility pre-check inspect?
It parses the server-returned HTML and checks detectable markup patterns such as image alt attributes, heading order, form labels including wrapping labels, empty links and buttons, duplicate IDs, page language, landmarks, skip links, zoom restrictions, and autoplay media. Findings are grouped under WCAG principles where applicable.
How should I interpret errors, warnings, and information items?
Errors indicate a strong machine-detectable problem, such as an unlabeled form field or missing page language. Warnings need context, such as several empty alt values that may be valid for decorative images. Information items are review prompts, not automatic failures. Start with errors, then verify every warning against the page design.
Is this an ADA or WCAG compliance checker?
No. It is an HTML pre-check that finds common markup problems a WCAG or ADA accessibility review would flag, such as missing alt attributes, unlabeled form fields, skipped heading levels, a missing page language and absent landmarks. It cannot judge whether alternative text is meaningful, test keyboard use, focus order or contrast, or check the page with a screen reader, so a clean result does not prove WCAG 2.2 or ADA compliance.
Why can JavaScript-rendered content be missing from the report?
The endpoint analyzes the HTML returned by the server. Controls, labels, dialogs, or images added only after client-side JavaScript runs may not appear in that response. Test dynamic states in a browser with a keyboard, screen reader, and a browser-based accessibility scanner.
Why can an empty alt attribute be a warning instead of an error?
An empty alt value is correct for a decorative image because it tells a screen reader to ignore it. The tool warns only when several empty values deserve review. Keep empty alt text for genuinely decorative images and write useful alternatives for images that communicate content or function.
What should I fix first after a failed scan?
Prioritize controls without accessible names, unlabeled form fields, missing page language, missing meaningful image alternatives, zoom restrictions, empty links, and duplicate IDs. After changing the markup, retest and manually check keyboard focus, visible focus, contrast, zoom, and screen-reader output.
Why might the checker fail to fetch a public page?
The page may time out, reject automated requests, require authentication, or block the scanner through a firewall or bot rule. The request follows redirects and waits up to about 12 seconds. A fetch failure says nothing about the page's accessibility.
What data is sent when I run the accessibility check?
The public URL is sent to the Web Aloha API so the server can fetch and analyze its returned HTML. The form asks for no name, email, login, or private page content, and the endpoint contains no application-storage step for the URL or report.

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