Yarn (JavaScript Package Manager)

Yarn is a package manager for JavaScript projects. It reads dependency requirements from a project's package configuration, resolves the packages and versions that are needed, and installs them so developers can use third-party libraries without managing each dependency manually.

A key part of Yarn's workflow is its lockfile, which records the resolved dependency graph so installations can be reproduced consistently across developer machines, CI environments, and production builds. Yarn also supports workspaces, allowing multiple related packages in a monorepo to share dependency-management tooling while remaining separate projects.

Yarn is commonly used with Node.js and frontend frameworks such as React. Its role is different from the Hadoop technology called YARN: the JavaScript tool manages software packages and project dependencies, while Hadoop YARN manages compute resources for distributed applications.