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core-js vs Opal

Based on 1599 and 1 real audits

View core-js details | View Opal details
Metriccore-jsOpalWinner
Performance3626core-js
Accessibility8882core-js
Best Practices8496Opal
SEO9192Opal
Security6572Opal
TTFB379ms436mscore-js
Composite7273Opal
Performance
core-js
36
Opal
26
Accessibility
core-js
88
Opal
82
Security
core-js
65
Opal
72
SEO
core-js
91
Opal
92
Composite
core-js
72
Opal
73

Opal outperforms core-js in 4 of 7 categories, with a stronger composite score (73 vs 72). core-js leads in performance, accessibility, TTFB.

When to choose core-js

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.

When to choose Opal

Choose Opal when your primary concern is best practices and security. Its audit data shows consistent strength in these areas across the sampled sites.

How this comparison was built

Scores are medians across 1599 audited core-js sites and 1 audited Opal 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 →

Small sample: one or both technologies have fewer than 10 audited sites. Treat these numbers as directional — medians stabilize around 20–30 audits per side.

FAQ

Which is faster, core-js or Opal?
Based on real BeaverCheck audits, core-js sites score higher on Lighthouse performance (36 vs 26 on average).
Which has better security, core-js or Opal?
Opal sites score higher on security analysis (72 vs 65 on average).
Which has better accessibility, core-js or Opal?
Accessibility scores measured by Lighthouse WCAG 2.1 checks favor core-js (88 vs 82). 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 Opal?
Opal sites score higher on Lighthouse SEO signals (92 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 Opal?
core-js sites show lower Time to First Byte (379 ms vs 436 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 Opal 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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