⌕ Test & Debug

Accessibility Checker

Audit HTML for WCAG 2.1 AA accessibility violations using axe-core — critical, serious, moderate, and minor issues.

Updated

axe-core WCAG 2.1 AA Live preview Grouped by severity

Loading Accessibility Checker…

What this page sends

  • Your input: The HTML is audited in the page and not sent to a server. Mounting it lets the browser request anything it references — images, stylesheets, fonts, iframes — so remove external URLs from sensitive markup first.
  • Page load: Loading the page requests HTML, scripts and images from ByteKiln, fonts from Google Fonts, and sends Google Analytics page views, tool-usage events and catalog interactions (tool/category IDs, result status and whether a click followed search — never your input, output or search terms). Privacy & sharing

How the Accessibility Checker Works

The ByteKiln Accessibility Checker uses axe-core, the industry-standard open-source accessibility engine, running in your browser to audit HTML snippets or full page markup. Resources your markup references, such as images, can be requested when it is mounted.

How axe-core works

The HTML is injected into a hidden off-screen div. axe-core traverses the DOM, runs its rule engine against each element, and returns violations, passes, incomplete checks, and inapplicable rules.

Violation grouping

Violations are sorted and grouped by impact: Critical, Serious, Moderate, Minor. Each card shows the rule ID, a description, affected node count, and expandable HTML snippets with failure summaries.

Live preview

Switch to the Preview tab to render your HTML in a sandboxed iframe. This lets you visually inspect the page and identify issues like low contrast or missing visual focus indicators before running the audit.

Limitations

  • axe-core finds the issues a rule engine can detect — typically well under half of WCAG problems. Keyboard operation, focus order, screen-reader announcements and meaningful alt text still need a person.
  • The snippet is mounted inside this page, so its color-contrast results can be affected by ByteKiln's styles and by stylesheets your markup doesn't load here.
  • Only the HTML you paste is checked: behaviour added later by JavaScript, other pages and PDFs are out of scope.
  • Mounting the markup lets the browser request images and other resources it references.

FAQ

Short answers for the things developers usually ask before trusting a tool.

What WCAG level does this check?

The checker runs axe-core with WCAG 2.0 Level A, WCAG 2.0 Level AA, WCAG 2.1 Level A, and WCAG 2.1 Level AA rules, plus best-practice rules. This covers the most common compliance requirements including ADA, Section 508, and EN 301 549.

What kinds of issues are detected?

Common violations include: images without alt text, form inputs without associated labels, insufficient color contrast, missing document language, incorrect heading hierarchy, links with non-descriptive text, tables without headers, and missing ARIA roles.

Is this a full accessibility audit?

Automated tools like axe-core can catch about 30–40% of WCAG violations. Keyboard navigation testing, screen reader testing, and cognitive load assessment require manual review. Use this tool as a starting point, not a complete audit.

Does my HTML get uploaded anywhere?

No. axe-core runs in your browser. The HTML is mounted in a hidden off-screen container, analysed, and the container is immediately removed. The HTML is not sent to a server, but mounting it can make the browser request resources it references, such as images or stylesheets, so strip external URLs from sensitive snippets.

What do the impact levels mean?

Critical: will block assistive technology users entirely. Serious: causes significant barriers. Moderate: causes some difficulty. Minor: best-practice violations that create minor friction. Fix Critical and Serious issues before launching.

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