Validate HTML for WCAG 2.1 compliance and detect common accessibility issues
Zero Dependencies · Works Offline📝 Paste HTML to Check
What Is the Web Accessibility Checker?
The Web Accessibility Checker is a free online tool that validates HTML code against WCAG 2.1 accessibility guidelines. It detects common accessibility issues like missing alt text on images, missing form labels, empty links and buttons, ARIA attribute problems, heading hierarchy issues, and missing document language. All checks run locally in your browser with no data uploaded to any server.
Core Features
- Image Alt Text Check: Detects images missing alt attributes
- Form Label Check: Finds form inputs without associated labels
- Empty Link/Button Check: Identifies links and buttons without accessible text
- ARIA Validation: Checks for invalid ARIA attributes and roles
- Heading Hierarchy: Validates heading order (h1→h2→h3)
- Document Language: Checks for missing lang attribute on html element
How to Use
1. Paste your HTML code into the input area.
2. Click "Check Accessibility" to run the analysis.
3. Review the issues list with severity levels and WCAG references.
4. Fix the issues in your code and re-check.
Understanding WCAG Levels
WCAG 2.1 defines three conformance levels: Level A (minimum accessibility, must be met), Level AA (standard accessibility, recommended for most websites), and Level AAA (enhanced accessibility, not required for most sites). This checker primarily focuses on Level A and AA issues that can be automatically detected.
Limitations of Automated Testing
Automated accessibility checkers can detect approximately 30-50% of WCAG issues. Many accessibility requirements — such as meaningful alt text, logical reading order, keyboard operability, and content clarity — require manual testing. Use this tool as a first pass, then supplement with manual testing and user testing with assistive technologies.
❓ FAQ
What is WCAG 2.1?
International standard for web accessibility with three levels: A (minimum), AA (standard), AAA (enhanced).
What does this checker look for?
Missing alt text, missing form labels, empty links/buttons, ARIA issues, heading hierarchy, missing lang attribute.
Is this a complete WCAG audit?
No. Automated tools detect 30-50% of issues. Manual testing is needed for full compliance.
Is my HTML data uploaded?
No. All checks run locally in your browser.
What is ARIA?
Accessible Rich Internet Applications — HTML attributes that make web content more accessible to screen readers.
How to fix color contrast?
WCAG AA requires 4.5:1 contrast for normal text, 3:1 for large text. Use our Color Contrast Checker.