Updated
core-js is a modular standard library for JavaScript that provides polyfills for ECMAScript up to 2023. It allows developers to use the latest JavaScript features across different environments and browsers, ensuring consistent behavior. core-js is highly configurable, letting developers include only the features they need, which helps in optimizing application size and performance.
core-js belongs toJavaScript librariescategory.
776websites
use it — 30.4% of the 2,555 websites we scanned in the last 12 months
#2of 108
tools in its category seen in our scans (we recognize 252)
119public pages
on UptimeCard — open any of them to see how that site is doing
Used on 30.4% of the websites we scan — and those sites load in 4.4 s, about the same as every other site (4.3 s). Installing it does not make a site noticeably slower.
39.58% of all websites we track run core-js▼ 0.05 points since 20 Sep
At a glance
UptimeCard's own scans and tests of 2,555 websites · refreshed weekly
How core-js sites scoreout of 100 · hover or tap a score for details
Page load time
Loads about as fast as the average site
Most core-js sites load in 3.2–6.7 s. Home page weight: 3.6 MB vs 3.3 MB for all sites. 109 public sites measured.
Where are they hosted?
Mostly Amazon Web Services and Cloudflare
- Amazon Web Services31%
- Cloudflare30%
- Fastly5%
- Google Cloud3%
- Other30%
Who uses it?
Software as a Service (SaaS) sites use core-js 1.7× more than average
Share of 119 classified public sites. “× average” compares with all 961 public sites.
Browser-security check
23% of graded sites pass
7of 31 score B or better
Rates each site’s own security settings, not core-js. 31 public sites graded so far.
How core-js sites are built
Closest partners. The number says how many times more often the tool runs on core-js sites than on an average website. Hover a partner for its share of sites.
Facebook Pixel2×
Lodash2×
Microsoft Clarity2×
jQuery UI2×Stacks we see most. Tools that tend to run together with core-js on the same websites. The percentage is the share of all 776 core-js sites that run the whole stack.
core-js + Bootstrap + cdnjs
core-js + Funding Choices + Google Sign-in
core-js + Akamai + Adobe Experience Manager
core-js + Elementor + Site Kit
core-js + Elementor + Hello Elementor
core-js + Elementor + RankMath SEO
core-js + Elementor + Contact Form 7
Usually installed alongside
The bigger the bubble, the more of the 776 core-js sites also run the tool. Colour shows what the tool does. Hover or tap a bubble for details.
Google Tag Manager72%
Google Analytics70%Facebook Pixel44%
Linkedin Insight Tag20%
Microsoft Advertising22%
OneTrust18%
Cart Functionality18%
HubSpot13%Similar tools in its category
JavaScript libraries: 252 tools known, 108 seen in our scans
jQuery1,030 sitesAlternative
lit-html155 sitesAlternativelit-element128 sitesAlternative
Slick98 sitesAlternative
Goober65 sitesAlternative
OWL Carousel52 sitesAlternative
AOS52 sitesAlternative
FancyBox42 sitesAlternative
Swiper285 sitesUsed togetherjQuery Migrate245 sitesUsed togetherjQuery UI217 sitesUsed togetherLodash184 sitesUsed togetherHow websites combine core-js with other tools
Relationships found on the websites that use it, from the same map status pages show.
Questions about core-js
- How many websites use core-js?
- We found core-js on 776 of the 2,555 websites we scanned in the last 12 months (30.4%). 119 of them have a public status page.
- What is core-js often used with?
- Among the websites we scan, core-js is often found alongside Google Analytics (69.7% of its sites), Facebook Pixel (43.9% of its sites), reCAPTCHA (27.2% of its sites).
- What are the alternatives to core-js?
- Other javascript libraries tools we recognize include jQuery, Swiper, jQuery Migrate, jQuery UI.
Is your website built with core-js?
UptimeCard checks it around the clock, tells you the minute it stops answering, and gives your visitors a status page.