npm, Yarn, and pnpm are all JavaScript package managers that install dependencies from the npm registry, but they differ in performance, disk usage, dependency resolution, and monorepo support. npm (Node Package Manager) is the default package manager bundled with Node.js, providing the baseline experience that all JavaScript developers start with. Yarn was created by Facebook in 2016 to address npm's early performance and reliability issues, introducing lockfiles and parallel downloads. pnpm (performant npm) takes a fundamentally different approach by using a content-addressable store and hard links to eliminate duplicate packages across projects.
The storage architecture difference between these tools is the most impactful distinction. npm creates a flat node_modules directory, hoisting dependencies to the top level. This approach can create phantom dependencies, where your code accidentally imports a package that is not in your package.json but is available because a dependency's dependency was hoisted. pnpm uses a unique nested structure with hard links to a global content-addressable store, meaning each package version exists only once on disk regardless of how many projects use it. A developer with 20 projects using React saves significant disk space because pnpm stores one copy of React and hard-links it into each project.
Installation speed follows from the storage design. pnpm is consistently the fastest because it checks the global store first and only downloads packages that are not already cached, then creates hard links instead of copying files. npm must copy all packages into the project's node_modules. In CI/CD environments where clean installs happen frequently, pnpm's speed advantage is measurable: large monorepos can see 2-3x faster installation times compared to npm.
Yarn has evolved into two distinct versions. Yarn Classic (1.x) behaves similarly to npm with a flat node_modules and a yarn.lock file. Yarn Berry (2.x+) introduced Plug'n'Play (PnP), which eliminates node_modules entirely and resolves dependencies from a .pnp.cjs file and compressed zip archives. PnP enables zero-install repositories (dependencies committed to git) and strict dependency enforcement, but it requires tooling support and can break packages that assume node_modules exists. The ecosystem compatibility overhead makes Yarn Berry a niche choice for teams willing to invest in the transition.
| Feature | npm | pnpm |
|---|---|---|
| Installation speed | Moderate (improved in npm 7+) | Fastest due to content-addressable storage |
| Disk space usage | Copies packages per project (node_modules) | Single global store, hard links to projects |
| Zero-install capability | Not supported | Not supported (Yarn PnP supports this) |
| Strict dependency resolution | Flat node_modules, phantom dependencies possible | Strict, only declared dependencies accessible |
| Monorepo support | Workspaces (npm 7+) | Workspace protocol with filtering |
| Pre-installed with Node.js | Yes, ships with every Node.js install | No, requires separate installation |
| Lockfile format | package-lock.json (JSON) | pnpm-lock.yaml (YAML) |
| Ecosystem compatibility | Universal, every package expects npm | Excellent, rare compatibility issues |
| Registry support | npmjs.com registry (default) | Same registry, same packages |
| Corepack integration | Managed via Node.js Corepack | Managed via Node.js Corepack |
Use npm for simplicity and universal compatibility since it ships with Node.js and every tutorial assumes it. Use pnpm for monorepos, CI/CD pipelines where disk and speed matter, and projects requiring strict dependency isolation. Yarn (Classic) is still used in legacy projects, while Yarn Berry (PnP) offers zero-install capability but requires ecosystem adjustment. For most new projects, npm or pnpm are the strongest choices.
For individual developers and small teams starting new projects, npm is the path of least resistance. It ships with Node.js, every tutorial and documentation page assumes npm, and it has improved dramatically in performance and features since version 7 (workspaces, improved lockfile, better performance). If you have no specific pain point with npm, there is limited reason to switch.
For monorepo projects with multiple packages, pnpm is the strongest choice. Its workspace protocol supports cross-package dependencies, the pnpm --filter command enables running scripts in specific packages, and strict dependency resolution prevents the phantom dependency issues that plague npm monorepos. Turborepo, Nx, and other monorepo tools work well with pnpm's workspace features. The disk space savings also matter in monorepos where many packages share common dependencies.
For CI/CD optimization, pnpm's content-addressable store and hard-linking strategy reduce both network downloads and disk I/O. When combined with a persistent cache, pnpm can provide near-instant installations in CI. npm's caching is less efficient for clean installs because it still copies packages into node_modules even when cached. If your CI pipeline's package installation step is a bottleneck, switching to pnpm is one of the highest-impact optimizations.
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Consider switching if you work with monorepos, want strict dependency resolution that prevents phantom dependencies, need faster CI installations, or want to save disk space across many projects. If you are a solo developer working on single-package projects with no performance concerns, npm is perfectly adequate and avoids the overhead of learning a new tool.
Yarn Classic (1.x) is in maintenance mode and no longer recommended for new projects. Yarn Berry (2.x+) with Plug'n'Play offers unique features like zero-install and strict dependency enforcement, but requires significant ecosystem buy-in. Most teams choosing a non-npm package manager now prefer pnpm for its balance of performance, compatibility, and strict resolution without requiring the breaking changes that Yarn PnP introduces.
You should not. Different package managers create different lockfile formats (package-lock.json, yarn.lock, pnpm-lock.yaml) and resolve dependencies differently. Mixing managers leads to inconsistent node_modules across team members and CI/CD, causing hard-to-debug build failures. Choose one package manager and enforce it via the engines field in package.json or use Corepack to manage the package manager version.
Phantom dependencies occur when your code imports a package that is not listed in your package.json but is available because npm or Yarn hoisted it from a transitive dependency. This works until the parent dependency removes or changes that transitive dependency, breaking your code. pnpm prevents phantom dependencies with its strict symlink structure where only packages declared in your package.json are accessible to your code.
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