core-js vs Immutable.js

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

Top sites by authority

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

United States 1,295,217

1,038

India 433,567

152

Brazil 406,300

110

United Kingdom 402,603

182

Germany 384,505

133

France 315,055

120

Italy 302,259

108

Canada 295,823

560

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, Sep 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 Immutable.js sites