Lighthouse

Chrome DevTools Accessibility & Performance Auditor

Built into Chrome DevTools

Free, comprehensive auditing for accessibility, performance, SEO, and best practices

Free

Built-in

Chrome

DevTools

Multi-Audit

Tool

What is Lighthouse?

Lighthouse is an open-source automated tool developed by Google that audits web pages for performance, accessibility, SEO, best practices, and Progressive Web App (PWA) features. It's built directly into Chrome DevTools, making it easily accessible to all developers.

While Lighthouse audits multiple aspects of web quality, its accessibility auditing capabilities are comprehensive and based on WCAG 2.1 Level A and AA success criteria. It provides detailed reports with specific recommendations for improving accessibility, making it an essential tool for developers and accessibility professionals.

Lighthouse can be run from Chrome DevTools, as a Chrome extension, from the command line, or as part of CI/CD pipelines. It generates detailed reports with scores (0-100) for each category, specific issues found, and actionable recommendations for improvement.

The accessibility audit in Lighthouse tests for common issues like missing alt text, insufficient color contrast, missing ARIA labels, improper heading hierarchy, and keyboard accessibility problems. It's particularly useful for getting a quick accessibility overview and identifying common violations.

Key Features

Accessibility Auditing

Tests WCAG 2.1 Level A and AA success criteria
Identifies common accessibility violations
Provides accessibility score (0-100)
Detailed issue descriptions and remediation guidance

Multi-Category Auditing

Performance auditing (Core Web Vitals)
SEO optimization checks
Best practices evaluation
Progressive Web App (PWA) features

Detailed Reporting

Color-coded scores for each category
Specific issues with code examples
Opportunities for improvement
Exportable reports (HTML, JSON)

Multiple Access Methods

Chrome DevTools (built-in)
Command line (lighthouse CLI)
Chrome extension
CI/CD integration (GitHub Actions, etc.)

How to Use Lighthouse

Using Lighthouse is straightforward, especially through Chrome DevTools:

Open Chrome DevTools: Navigate to the page you want to test, then press F12 (or Cmd+Option+I on Mac) to open DevTools.

Open Lighthouse Tab: Click on the "Lighthouse" tab in DevTools (if not visible, click the ">>" icon to see more tabs).

Select Categories: Choose which categories to audit (Accessibility, Performance, SEO, Best Practices, PWA). For accessibility testing, ensure "Accessibility" is checked.

Choose Device: Select "Desktop" or "Mobile" to simulate different devices.

Run Audit: Click "Analyze page load" to start the audit. Lighthouse will analyze the page and generate a report.

Review Results: Review the accessibility score and issues found. Click on each issue to see details and recommendations.

What Lighthouse Accessibility Tests

Lighthouse accessibility audit checks for many WCAG violations:

Common Issues:

✓ Missing alt text on images
✓ Insufficient color contrast
✓ Missing form labels
✓ Missing page title
✓ Improper heading hierarchy
✓ Missing ARIA attributes
✓ Keyboard accessibility
✓ Missing document language

Additional Checks:

✓ ARIA usage and validity
✓ List structure
✓ Table structure
✓ Link purpose clarity
✓ Focus indicators
✓ Meta viewport configuration
✓ Video/audio captions

Note: Lighthouse provides a good accessibility overview but doesn't catch all issues. Combine with manual testing and other tools like axe DevTools for comprehensive coverage.

Understanding Lighthouse Scores

Lighthouse provides scores from 0-100 for each category:

90-100 (Green)Excellent - Few or no issues

50-89 (Orange)Needs Improvement - Some issues found

0-49 (Red)Poor - Many critical issues

Aim for 90+ accessibility score. However, remember that automated tools can't catch all accessibility issues - manual testing is still essential.

Command Line Usage

Lighthouse can also be run from the command line for CI/CD integration:

# Install Lighthouse

npm install -g lighthouse

# Run accessibility audit

lighthouse https://example.com --only-categories=accessibility

Command line usage is ideal for automated testing in CI/CD pipelines and batch testing multiple pages.

Best Practices

Test Regularly: Run Lighthouse audits during development, not just before release
Fix High-Impact Issues: Prioritize issues that affect the most users or are easiest to fix
Test Both Desktop and Mobile: Run audits for both device types as issues can differ
Combine with Other Tools: Use Lighthouse alongside axe DevTools and manual testing
Export Reports: Save reports for tracking improvements over time
Integrate into CI/CD: Use Lighthouse CLI in automated testing pipelines

Find Jobs Using Lighthouse

Looking for accessibility jobs that require Lighthouse? Browse our latest opportunities.

Last Updated: January 2025