"Yarn 11,798 " names two programs. Yarn Classic 11,798 (1.x) is a faster, stricter npm 2,036 client from 2016. Yarn Berry (2 and later, named after its yarnpkg/berry repository) is a rewrite that can drop node_modules entirely. Both write yarn.lock, in incompatible formats. A third generation, Yarn 6, rewritten in Rust, was in preview in September 2026.