Based on 1688 and 353 real audits
| Metric | core-js | Microsoft Clarity | Winner |
|---|---|---|---|
| Performance | 36 | 33 | core-js |
| Accessibility | 88 | 89 | Microsoft Clarity |
| Best Practices | 84 | 83 | core-js |
| SEO | 91 | 92 | Microsoft Clarity |
| Security | 66 | 65 | core-js |
| TTFB | 396ms | 402ms | core-js |
| Composite | 73 | 72 | core-js |
core-js outperforms Microsoft Clarity in 5 of 7 categories, with a stronger composite score (73 vs 72). Microsoft Clarity leads in accessibility, SEO.
Choose core-js when your primary concern is server response time and performance. Its audit data shows consistent strength in these areas across the sampled sites.
Choose Microsoft Clarity when your primary concern is accessibility and SEO. Its audit data shows consistent strength in these areas across the sampled sites.
Scores are medians across 1688 audited core-js sites and 353 audited Microsoft Clarity sites in the BeaverCheck database. Every audit runs the same 100+ checks — Lighthouse performance, security headers, accessibility, SEO, server response time — against a real URL. No vendor input, no sponsorship, no affiliate links. Read the full methodology →
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