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core-js vs Optimizely

Based on 1582 and 125 real audits

View core-js details | View Optimizely details
Metriccore-jsOptimizelyWinner
Performance3632core-js
Accessibility8890Optimizely
Best Practices8487Optimizely
SEO9191Tie
Security6565Tie
TTFB374ms186msOptimizely
Composite7272Tie
Performance
core-js
36
Optimizely
32
Accessibility
core-js
88
Optimizely
90
Security
core-js
65
Optimizely
65
SEO
core-js
91
Optimizely
91
Composite
core-js
72
Optimizely
72

Optimizely outperforms core-js in 3 of 7 categories, with a stronger composite score (72 vs 72). core-js leads in performance.

When to choose core-js

Choose core-js when your primary concern is performance. Its audit data shows consistent strength in these areas across the sampled sites.

When to choose Optimizely

Choose Optimizely when your primary concern is server response time and best practices. Its audit data shows consistent strength in these areas across the sampled sites.

How this comparison was built

Scores are medians across 1582 audited core-js sites and 125 audited Optimizely 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 →

FAQ

Which is faster, core-js or Optimizely?
Based on real BeaverCheck audits, core-js sites score higher on Lighthouse performance (36 vs 32 on average).
Which has better security, core-js or Optimizely?
core-js sites score higher on security analysis (65 vs 65 on average).
Which has better accessibility, core-js or Optimizely?
Accessibility scores measured by Lighthouse WCAG 2.1 checks favor Optimizely (90 vs 88). Both technologies can be made fully accessible with care — the difference reflects common patterns in the sampled sites, not inherent platform limits.
Which is better for SEO, core-js or Optimizely?
core-js sites score higher on Lighthouse SEO signals (91 vs 91 on average), which cover meta tags, crawlability, mobile friendliness, and structured data. Content strategy and backlinks still matter more than platform choice for ranking.
Which has faster server response (TTFB), core-js or Optimizely?
Optimizely sites show lower Time to First Byte (186 ms vs 374 ms on average). TTFB depends heavily on hosting and CDN setup rather than the technology itself, but the sampled sites suggest a meaningful difference in common deployment patterns.
Should I choose core-js or Optimizely for my website?
Both platforms have trade-offs. core-js scores higher on overall composite score while core-js may excel in metrics you care about most. Run a free BeaverCheck audit on a real site using each to compare the metrics relevant to your use case.
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