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ValidateHTML

HTML Accessibility Checker

Find accessibility issues in your HTML code. Check for missing alt attributes, heading hierarchy problems, ARIA issues, and WCAG compliance.

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Common HTML Accessibility Issues

Missing Alt Attributes

error

Every <img> element must have an alt attribute describing the image content. Screen readers rely on this text to convey image meaning.

Incorrect Heading Hierarchy

warning

Headings should follow a logical order (h1 → h2 → h3). Skipping levels makes it harder for screen reader users to navigate.

Missing Form Labels

error

Form inputs must have associated <label> elements or aria-label attributes for screen reader users.

Missing Language Attribute

warning

The <html> element should include a lang attribute to help screen readers pronounce content correctly.

Empty Links and Buttons

error

Links and buttons must have discernible text. Icon-only buttons need aria-label attributes.

Missing Document Title

error

Every page needs a <title> element. It is the first thing announced by screen readers.

Why Web Accessibility Matters

Web accessibility ensures that websites are usable by everyone, including people with disabilities. Over 1 billion people worldwide live with some form of disability.

Beyond the ethical imperative, accessibility is increasingly a legal requirement. The European Accessibility Act (EAA), Americans with Disabilities Act (ADA), and WCAG set standards that websites must meet.

Accessible HTML also improves SEO. Search engines use similar signals to screen readers: clear heading hierarchy, descriptive alt text, and semantic markup all help search engines understand your content better.

Frequently Asked Questions

What is web accessibility?
Web accessibility means designing and building websites that can be used by everyone, including people with visual, auditory, motor, or cognitive disabilities. This includes users who rely on screen readers, keyboard navigation, voice control, or other assistive technologies. Accessible websites follow standards like WCAG to ensure equal access to information and functionality.
What is WCAG and which version should I follow?
WCAG (Web Content Accessibility Guidelines) is the international standard for web accessibility, published by the W3C. WCAG 2.1 Level AA is the most widely adopted standard and is referenced by most accessibility laws. WCAG 2.2 was released in 2023 and adds additional criteria. Most organizations should target WCAG 2.1 AA as a minimum.
Why does accessibility matter for SEO?
Accessibility and SEO share many overlapping best practices. Search engines rely on similar signals to screen readers: clear heading hierarchy, descriptive alt text, semantic HTML, proper link text, and logical page structure. Improving accessibility almost always improves SEO, as it makes your content more understandable to both machines and humans.
What are ARIA labels and when should I use them?
ARIA (Accessible Rich Internet Applications) labels provide additional context to assistive technologies when native HTML semantics are not sufficient. Use aria-label to name interactive elements like icon-only buttons, aria-describedby to link descriptions, and role attributes to define custom widget behavior. However, prefer native HTML elements over ARIA when possible. A <button> is better than <div role="button">.
How is this checker different from Lighthouse, WAVE, or axe?
Lighthouse runs a full accessibility audit through Chrome DevTools but requires a deployed page to test. WAVE and axe are browser extensions that test pages already loaded in a browser. Our checker is designed for code review: paste raw HTML before deployment to catch issues earlier in the workflow. The three approaches complement each other rather than replace one another, and our rules are aligned with axe-core conventions.
Will this checker make my site ADA or EAA compliant?
No automated tool can guarantee full ADA, EAA, or WCAG compliance on its own. Automated checkers catch roughly 30 to 40 percent of accessibility issues. Manual testing with screen readers, keyboard navigation, and real users with disabilities is required to cover the rest. Use this tool as a first pass, then complement it with manual audits before claiming compliance.
Is this accessibility checker free?
Yes, our HTML accessibility checker is completely free. Paste your HTML code to instantly find accessibility issues including missing alt attributes, heading hierarchy problems, missing form labels, ARIA issues, and more. No registration required.