What is npm? The Node.js Package Manager Explained

Every modern JavaScript project, whether frontend or backend, depends on third-party libraries. Managing those dependencies manually would be a nightmare. That’s where npm comes in.

What is npm?

The Node Package Manager (npm) is the default package manager for Node.js. It lets developers:

• Install libraries (packages) from the public npm registry.
• Manage dependencies in a project via a package.json file.
• Publish custom packages for others to use.
• Version-control libraries and ensure reproducible builds with a lockfile (package-lock.json).

npm comes automatically when you install Node.js, so it’s the most widely used package manager in the JavaScript ecosystem.

Why Do We Need npm?

JavaScript applications rely heavily on third-party modules, frameworks, UI components, build tools, linters, and more. Without a package manager like npm, developers would need to manually download and include each dependency, track versions, and handle nested dependencies themselves.

npm solves this by:

• Centralizing package discovery in one registry.
• Ensuring consistent dependency resolution across environments.
• Automating installation, updates, and publishing.
• Supporting scripts (npm run) to manage build and deployment tasks.

In short: npm is the backbone of JavaScript dependency management.

Alternatives to npm

While npm is the default, two popular alternatives have emerged:

• Yarn (by Meta), introduced in 2016 to improve performance and reliability.
• pnpm, focused on disk efficiency and speed through content-addressable storage.

Each offers different trade-offs depending on your project size, team workflow, and CI/CD setup.

Real-World Example: Installing Dependencies for a React App

Let’s say you’re setting up a new React project:

npm install react react-dom
# or
yarn add react react-dom
# or
pnpm add react react-dom

All three commands achieve the same result, adding react and react-dom, but they differ in speed, storage, and node_modules structure.

npm

• Pros

  • Official and most universally supported.
  • Strong integration with the npm registry.
  • Reliable and improving with every version.

• Cons

  • Historically slower (though greatly improved in v7+).
  • Creates deep, redundant node_modules trees (uses more disk).

• Performance

  • Moderate install time; larger storage footprint.

Yarn

• Pros

  • Parallel installs make it faster than older npm versions.
  • Uses a deterministic lockfile (yarn.lock).
  • Excellent caching and offline capabilities.

• Cons

  • Two major versions with different behaviors (v1 vs Berry).
  • Compatibility issues with some npm scripts.

• Performance

  • Slightly faster than npm; moderate disk usage.

pnpm

• Pros

  • Symlink-based storage drastically reduces disk usage.
  • Very fast installs after the first run (shared global cache).
  • Strict dependency isolation improves reproducibility.

• Cons

  • Slightly less common in older CI pipelines.
  • Some tools may require configuration tweaks.

• Performance

  • Fastest install time; lowest disk usage.

Performance and Storage Comparison

(🟢 = good, 🟡 = average, 🔴 = weak)

Understanding Each Criterion

Install Speed (Cold)

A cold install means installing packages from scratch, no prior cache on disk. When you run:

npm install

on a new machine or a fresh Continuous Integration (CI) runner such as GitHub Actions or GitLab CI, npm downloads every dependency from the npm registry. This can take time because npm creates deeply nested folders for dependencies, which increases I/O operations.

• npm (🟡 Medium) → Installs all packages sequentially and writes them fully to node_modules, creating duplicates for shared sub-dependencies.
• Yarn (🟢 Fast) → Installs in parallel and uses a better caching system than older npm versions.
• pnpm (🟢 Fast) → Uses a content-addressable storage system and symlinks dependencies, avoiding redundant downloads after the first run.

Example: Installing a fresh React + TypeScript project (≈ 1,000 dependencies):

• npm: ~65 seconds
• Yarn: ~45 seconds
• pnpm: ~40 seconds

Note: The times above are illustrative benchmarks measured on a mid-range developer machine under normal network conditions. Actual results may vary depending on hardware performance, network speed, and project complexity. The goal is to highlight the relative differences between npm, Yarn, and pnpm.

That’s why npm is rated Medium, while Yarn and pnpm are Fast on cold installs.

Install Speed (Cached)

A cached install happens when you reinstall dependencies already downloaded once, e.g., when you run:

npm install

after deleting node_modules but keeping the cache.

• npm (🟢 Fast) → Caches tarballs locally, so reinstallation skips downloading.
• Yarn (🟢 Fast) → Excellent caching, reuses previous packages almost instantly.
• pnpm (🟢🟢 Very Fast) → The fastest, because it doesn’t duplicate packages at all, it links them directly from a global store.

Example: After the initial install above, a cached install runs in:

• npm: ~15 seconds
• Yarn: ~12 seconds
• pnpm: ~8 seconds

Note: The times above are illustrative benchmarks measured on a mid-range developer machine under normal network conditions. Actual results may vary depending on hardware performance, network speed, and project complexity. The goal is to highlight the relative differences between npm, Yarn, and pnpm.

pnpm’s shared store architecture gives it the clear edge here.

Disk Usage

This refers to the total space used by the node_modules folder and any related package cache.

• npm (🔴 High) → Duplicates many sub-dependencies, often resulting in gigabytes of disk usage in large projects.
• Yarn (🟡 Medium) → Slightly more efficient, but still stores many copies of packages.
• pnpm (🟢 Low) → Uses symlinks to a central content-addressable storage. The same dependency shared by multiple projects is only stored once.

Example: The same React + TypeScript project might use:

• npm: ~1.2 GB
• Yarn: ~800 MB
• pnpm: ~400 MB

Note: The sizes above are illustrative benchmarks measured on a mid-range developer machine under normal network conditions. Actual results may vary depending on hardware performance, network speed, and project complexity. The goal is to highlight the relative differences between npm, Yarn, and pnpm.

This is a major reason why pnpm is preferred for large monorepos or CI/CD environments.

Monorepo Support

A monorepo is a single repository that contains multiple related projects, e.g., a frontend, backend, and shared library all managed together. Workspaces are a package manager feature that allows dependencies to be shared intelligently between those subprojects.

• npm (🟡 Basic) → Introduced npm workspaces relatively recently, but lacks advanced tooling and performance optimization.
• Yarn (🟢 Strong) → Introduced Yarn Workspaces early, and they are widely adopted in large organizations.
• pnpm (🟢🟢 Excellent) → Designed from the ground up for monorepos. Offers automatic linking, shared caches, and fast install times across many subprojects.

Example: In a monorepo with:

• frontend/ (Next.js)
• backend/ (NestJS)
• shared/ (UI + TypeScript types)

You might see:

• npm installs everything separately per project.
• Yarn links shared dependencies automatically.
• pnpm does the same instantly, with minimal disk space and the best caching.

That’s why pnpm earns “Excellent”, it handles hundreds of workspace packages with speed and efficiency.

Community & Ecosystem

The community and ecosystem reflect how mature, supported, and well-integrated a tool is across frameworks and CI/CD systems.

Because npm was released first and bundled with Node.js, it naturally built the largest ecosystem over time. Yarn gained traction for speed and reliability, while pnpm is the newer, high-performance choice gaining popularity quickly in large-scale projects.

When to Choose Each

Conclusion

The Node Package Manager (npm) is the heart of JavaScript dependency management, essential for both frontend and backend development. Alternatives like Yarn and pnpm offer better speed or storage optimization, but npm remains the universal baseline for compatibility and ecosystem support.

If your priority is simplicity and reliability, stick with npm. If you want maximum performance and minimal disk usage, give pnpm a try.