Lighthouse and axe-core are the two automated accessibility scanners most teams reach for. They share a heritage (Lighthouse's a11y category embeds axe-core), but they catch different things in practice. We ran both against 50 production websites — here's what we found.
The setup
- 50 sites, mix of e-commerce, SaaS, and content (avg 8 issues/site between the two).
- Lighthouse 11 (default a11y category, mobile preset).
- axe-core 4.9 with rules at
wcag2a, wcag2aa, wcag21a, wcag21aa, wcag22aa.
Results
| Metric | Lighthouse | axe-core 4.9 |
|---|---|---|
| Avg issues found per site | 4.2 | 7.8 |
| Unique rules triggered | 27 | 56 |
| WCAG 2.2 coverage | partial | full |
| False positive rate (manual review) | ~5% | ~3% |
What axe-core catches that Lighthouse misses
- WCAG 2.2 target-size violations (2.5.8).
- ARIA misuse on custom widgets (axe is much stricter on role/state mismatch).
- Region/landmark issues on complex layouts.
- Color contrast on text inside images (axe has better OCR-aware checks).
What Lighthouse adds
- Performance correlation: an accessibility score next to LCP/CLS gives leadership a single dashboard.
- Crawl-style scoring out of 100, easier to track over time at a high level.
Verdict
Use both. Lighthouse is great for tracking a top-line score in CI dashboards. axe-core is what you want when you need to fix issues — its rule set is broader, its node-level reporting is more actionable, and it's the engine behind most professional audits. AccessProof runs axe-core under the hood, mapped to WCAG 2.2 and exportable as PDF.