core-js vs Day.js

Head-to-head usage across the sites we track.

Top sites by authority

core-js · Day.js · how many of each technology's sites sit in the web's highest authority tiers

Open Page Rank scores 0 to 10 from the open web link graph; 9+ covers only a few hundred domains worldwide.

By country

core-js · Day.js · share of sites in each country using one or the other

United States 1,320,418

14,927

India 439,882

5,745

Brazil 411,231

3,785

United Kingdom 404,005

4,842

Germany 391,462

4,620

France 311,727

3,976

Canada 298,167

3,778

Italy 291,018

3,012

Audience countries from the Chrome UX Report, top markets of either technology.

Real user performance

Median site's p75 values from the Chrome UX Report, Aug 2026. Lower is better; green meets Google's "good" threshold. This describes the sites that use each technology, not the technology's own overhead.

Sites that switched

Domains that dropped one technology and adopted the other within about a year, data nobody else gives away free.

All core-js sites · All Day.js sites