pnpm is an open-source package manager for JavaScript, a tool that downloads and installs the libraries (dependencies) a project uses. Its site presents it as a drop-in replacement for npm, and its benchmarks report installs up to 69 times faster than npm in one of six measured scenarios.
pnpm stores every file once in a content-addressable store, a store where each file is found by a hash of its content, and creates hard links to those files in each project's node_modules folder; 100 projects that use the same version cost one copy on disk. Only declared dependencies appear at the root of node_modules, so code cannot import a package it never declared. Workspaces support monorepos, repositories that hold several projects: a pnpm-workspace.yaml file lists the projects, the workspace: protocol links local packages to each other, filters run tasks only on selected projects, and one lockfile covers everything. Install scripts of dependencies run only when approved.
pnpm is free and open source under the MIT license.