Yarn

Yarn is a JavaScript package manager that Facebook created in 2016 as an alternative to npm, addressing speed and reliability issues at the time. Yarn Classic (1.x) introduced lockfiles and parallel downloads to the Node.js ecosystem, driving the entire package management landscape forward.

Yarn Modern (Berry, 2.x+) reimagined the architecture with Plug'n'Play — a strategy that eliminates the node_modules directory in favor of a single .pnp.cjs file mapping packages to their locations. Yarn natively supports workspaces for monorepo management and provides deterministic dependency resolution with offline caching. The project is developed on GitHub.