As of October 8, 2026, core-js is used by 9,046,687 websites in the TechLeads index: 6.9% of all JavaScript libraries detections, the 3rd most-used of 357 JavaScript libraries technologies.
9,046,687
websites using core-js
6.9%
share of JavaScript libraries
#3
of 357 in JavaScript libraries
Cite this data
Quoting these numbers? Credit TechLeads with a link to this page.
Citation
TechLeads. "core-js Customers and Market Share." Data as of October 8, 2026. https://techleads.fyi/technology/core-js/market-share
In HTTP Archive's monthly crawl of public websites, core-js was detected on 20,296,277 pages in September 2026, down 8.9% from a year earlier (peak: 23,523,716). Among the 1,000 most-visited sites, it appeared on 1,081. HTTP Archive is a separate dataset from the TechLeads index, so its numbers are not added to ours.
Same month, other JavaScript Libraries technologies in HTTP Archive: jQuery 32,400,479, jQuery Migrate 14,931,388, jQuery UI 10,564,965, Swiper 7,844,933, Lodash 4,107,763.
TechLeads scans public websites and detects core-js from signals in the page HTML, scripts, cookies, HTTP headers and DNS records. Market share is core-js's website count divided by the website counts of all JavaScript libraries technologies we track; a site using two JavaScript libraries tools counts for both. Counts were last refreshed on October 8, 2026 and update daily.
FAQ
core-js accounts for 6.9% of JavaScript libraries detections in the TechLeads index (9,046,687 websites), which makes it the 3rd most-used of 357 JavaScript libraries technologies we track.