Audit HTML for WCAG 2.1 AA accessibility violations using axe-core — critical, serious, moderate, and minor issues.
The ByteKiln Accessibility Checker uses axe-core, the industry-standard open-source accessibility engine, running entirely in your browser to audit HTML snippets or full page markup.
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.
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.
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.
Short answers for the things developers usually ask before trusting a tool.
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.
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.
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.
No. axe-core runs entirely in your browser. The HTML is mounted in a hidden off-screen container, analysed, and the container is immediately removed. Nothing leaves your browser.
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.
Useful follow-ups when one conversion usually turns into three more.
Collapse HTML markup, remove comments, and preview smaller output instantly.
Extract color palettes from images or build them manually. Export to CSS variables, Tailwind config, SCSS, or JSON with WCAG contrast grades.
Format, validate, and minify JSON instantly with a browser-first editor.