Accessibility Checker Online — Free WCAG Compliance Scanner

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How to Accessibility Checker Online

1. 1

   Paste your HTML document, component snippet (React, Vue, Svelte), or template markup into the input editor. The validator processes both complete pages and partial fragments seamlessly without requiring doctype or html boilerplate.

2. 2

   The scanner executes 40+ WCAG 2.2 rules locally in your browser, generating an overall accessibility health score (0–100) alongside individual Level A, AA, and AAA compliance ratings.

3. 3

   Select your target WCAG conformance tier (Level A, Level AA, or Level AAA). Level AA represents the standard legal baseline for ADA Title II, Section 508, and the European Accessibility Act (EAA).

4. 4

   Inspect the score overview to review issue distributions across Critical, Serious, Moderate, and Minor severity tiers, along with total evaluated DOM elements and rule passes.

5. 5

   Filter by severity or category (Images, Forms, Headings, ARIA, Color Contrast, Keyboard, Landmarks, Links, Tables, Multimedia) to prioritize high-impact blockers.

6. 6

   Expand any flagged issue card to inspect the offending HTML element, exact line and column numbers, a clear explanation of assistive technology impact, and automated code fix suggestions.

7. 7

   Click "Explain with AI" on complex violations to receive contextual guidance on screen reader behavior, affected user groups, and compliant code implementations.

8. 8

   Export your audit as a formatted Markdown summary for GitHub pull requests and Jira tickets, or copy structured JSON output for automated CI/CD pipeline integration.

Accessibility Checker Features

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  40+ Static WCAG 2.2 Audits: Evaluates HTML across 12 distinct categories including non-text contrast, target sizes, ARIA roles, form controls, and keyboard navigation.

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  Multi-Tier Conformance Scoring: Calculates granular compliance pass-rates across WCAG Level A, Level AA, and Level AAA success criteria.

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  Weighted Health Scoring Algorithm: Deducts points based on issue severity to ensure critical blockers are surfaced without overwhelming scores from minor formatting quirks.

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  Inline CSS Color Contrast Analysis: Calculates relative luminance and contrast ratios (4.5:1 for body text, 3:1 for large text/UI components) across Hex, RGB, HSL, and named CSS colors.

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  Fragment & Component Friendly: Seamlessly audits raw HTML fragments, email templates, and frontend component templates without requiring doctype or html boilerplate.

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  Automated Fix Code Generator: Produces ready-to-paste remediated HTML code snippets for common issues like missing alt tags, unassociated labels, and improper button roles.

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  Keyboard Operability & Tabindex Checks: Detects positive tabindex anti-patterns, missing keyboard handlers on clickable divs, and missing skip-to-content links.

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  ARIA Role & Attribute Validation: Verifies required ARIA properties, validates role hierarchies, and flags redundant or invalid ARIA declarations.

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  Heading Hierarchy Validator: Scans for missing H1 tags, skipped heading levels (e.g., H2 directly to H4), and empty heading containers.

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  Zero-Dependency Client-Side Engine: Executes entirely within browser memory using native parsing algorithms without sending proprietary HTML to external servers.

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  Exportable Reports: One-click export to Markdown for pull requests, issue trackers, and design-handoff documentation, plus raw JSON for tooling pipelines.

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  REST API & CI/CD Ready: Programmatically query the audit engine via POST /api/tools/a11y-checker to enforce accessibility checks in automated test suites.

Frequently Asked Questions

What WCAG version and conformance levels does this accessibility checker evaluate?

The scanner tests against 40+ rules derived from WCAG 2.0, 2.1, and 2.2 across Levels A, AA, and AAA. It inspects key success criteria including 1.1.1 (Non-text Content), 1.3.1 (Info and Relationships), 1.4.3 (Contrast Minimum), 2.1.1 (Keyboard Navigation), 2.4.4 (Link Purpose), 2.4.6 (Headings and Labels), 2.5.8 (Target Size), 3.1.1 (Language of Page), and 4.1.2 (Name, Role, Value).

What is the difference between WCAG Level A, AA, and AAA compliance?

WCAG conformance is divided into three tiers: Level A represents the essential baseline, where failures completely prevent users with disabilities from accessing content. Level AA is the global industry and legal benchmark (required by ADA, Section 508, and the European Accessibility Act), addressing major barriers across contrast, navigation, and form inputs. Level AAA provides enhanced accessibility for specialized environments, such as 7:1 contrast ratios and sign language interpretation.

How do I fix missing accessible names on icon buttons and SVG elements?

Interactive elements like icon-only buttons (<button><svg>...</svg></button>) require an accessible name so screen readers can announce their purpose. Fix this by adding an aria-label="Search" attribute to the <button> element, or by nesting a visually hidden <span class="sr-only">Search</span> inside the button. For decorative SVGs, set aria-hidden="true" and focusable="false".

How does the checker analyze color contrast from inline CSS styles?

The engine extracts foreground and background colors declared in inline style attributes (supporting Hex, rgb(), hsl(), and standard CSS color names) and computes relative luminance using the standard WCAG formula. It flags text elements that fail the minimum 4.5:1 contrast threshold for normal text or 3:1 for large text (18pt+ or 14pt+ bold).

How does the tool detect broken heading hierarchies and skipped levels?

The validator constructs a heading outline tree from <h1> through <h6> tags in your HTML. It checks that documents contain a primary <h1> landmark and flags skipped levels (such as jumping directly from <h2> to <h4>), which disorients screen reader users navigating pages via heading shortcut keys.

Can I audit partial HTML fragments, JSX components, and email templates?

Yes. The parser supports partial HTML fragments without requiring <!DOCTYPE html>, <html>, or <body> wrappers. Document-level checks (like <html lang> and <title>) are conditionally bypassed when testing fragments, while element-level rules (like form labels, image alt attributes, and ARIA roles) are evaluated normally.

Why should positive tabindex values be avoided in modern HTML?

Setting tabindex="1" or any positive integer disrupts natural DOM focus order, creating confusing navigation leaps for keyboard users. Accessible layouts rely on logical DOM source order with tabindex="0" to make non-interactive elements focusable when necessary, or tabindex="-1" for programmatic focus management.

How is the weighted accessibility score calculated?

The health score starts at 100 points. Points are deducted based on rule severity: Critical issues deduct 10 points, Serious deduct 5 points, Moderate deduct 2 points, and Minor deduct 1 point. Deductions within each severity bucket are capped to prevent a cluster of minor warnings from overshadowing primary compliance health.

How does static HTML scanning compare to live DOM audit tools like axe DevTools or Lighthouse?

Static HTML checking provides instant feedback during code authoring, linting, and pre-commit reviews before code is deployed. Live tools like axe DevTools or Lighthouse run inside a real browser DOM, which enables testing computed styles, dynamic JavaScript mutations, and active focus traps. Using both static pre-commit validation and live browser audits provides complete accessibility coverage.

How do I automate accessibility checks in CI/CD pipelines using the API?

You can send HTTP POST requests to /api/tools/a11y-checker with a JSON payload containing { html: "<your-markup>", wcagLevel: "AA" }. The endpoint returns structured JSON containing total score, categorized issues, line numbers, and remediation suggestions, allowing you to fail CI builds if scores fall below compliance thresholds.

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