Krati Joshi

One of the most confusing topics for beginners in Node.js isn't Express, APIs, or asynchronous programming—it's understanding where npm packages should be installed.

When I started learning Node.js, I thought there were only two commands:

npm install package-name

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and

npm install -g package-name

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I knew they both installed packages, but I had no idea when to use which one. Eventually, I realized they solve two completely different problems.

If you're learning Node.js, this article will save you from one of the most common beginner mistakes.

First, What Does npm Actually Do?

npm (Node Package Manager) is the package manager that comes with Node.js.

It helps you:

  • Install libraries
  • Manage project dependencies
  • Update packages
  • Share your own packages
  • Run project scripts

Whenever you install a package, npm has to decide where to install it.

That's where local and global installations come in.

Local Installation (The Default)

When you run:

npm install express

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npm installs Express inside your current project.

Your folder now looks something like this:

my-project/
│
├── node_modules/
├── package.json
├── package-lock.json
└── app.js

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It also adds Express to your package.json:

{
  "dependencies": {
    "express": "^5.0.0"
  }
}

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This means:

  • Express belongs to this project.
  • Anyone who clones your repository can simply run: 
npm install

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and npm installs everything automatically.

That's exactly what you want for project dependencies.

Why Local Installation Matters

Imagine you're building an API.

Your code contains:

const express = require("express");

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Now imagine another developer clones your project.

If Express was installed locally, they only need to run:

npm install

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Everything works.

If it wasn't, they'll see something like:

Cannot find module 'express'

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because the dependency isn't part of the project.

That's why libraries your application depends on should almost always be installed locally.

Global Installation

Now consider this command:

npm install -g nodemon

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This installs nodemon globally on your computer.

Instead of living inside a project, it's available from any terminal.

You can now run:

nodemon app.js

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from any project on your machine.

Global packages are mainly meant for command-line tools (CLI tools) rather than libraries used by your application.

Common Global Packages

Some examples include:

  • nodemon
  • typescript
  • npm
  • pm2
  • eslint (if you prefer using it globally)

These provide commands that you use while developing rather than becoming part of your application's runtime.

A Common Beginner Mistake

Many beginners do this:

npm install -g express

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It works on their machine because Express is installed globally.

Then they push their code to GitHub.

Another developer clones the repository and gets:

Error: Cannot find module 'express'

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Why?

Because global packages are not shared with your project.

They only exist on your own computer.

The correct way is:

npm install express

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Now Express becomes part of the project and is recorded in package.json.

So When Should You Install Globally?

Ask yourself one simple question:

Is this package used by my project, or by me?

If the project needs it:

âś… Install locally

npm install package-name

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If you need the command across many projects:

âś… Install globally

npm install -g package-name

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This simple rule avoids most confusion.

What About npx?

Modern Node.js development has made global installations less necessary.

Instead of installing a CLI globally, you can often use:

npx nodemon app.js

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or

npx create-react-app my-app

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npx will use the local package if it's already installed, or temporarily fetch and execute it when appropriate.

That means:

  • No global installation
  • No version conflicts between projects
  • Cleaner development environment

This is why you'll see npx recommended in many official tutorials.

Quick Comparison

Local Installation Global Installation
Inside current project Installed on your computer
Saved in package.json Not saved in project
Used by project code Used by developers
Shared with team Personal to your machine
Installed with npm install Installed with npm install -g

My Rule of Thumb

Whenever I'm unsure, I remember this:

  • 📦 If my application needs it → Install locally
  • 🖥️ If I need the command everywhere → Install globally
  • ⚡ If I only want to run it once → Use npx

This simple mindset has helped me avoid a lot of confusion while learning Node.js.

Final Thoughts

Understanding the difference between local and global packages isn't just about memorizing commands—it's about understanding who the installation is for.

  • Your application depends on local packages.
  • You, the developer, benefit from global CLI tools.
  • And npx gives you a convenient way to run many tools without installing them globally.

It's a small concept, but getting it right makes working with Node.js projects much smoother.

Thanks for reading! đź‘‹

I'm currently documenting my Node.js learning journey through the Backend Internals series. If you're learning Node.js too, feel free to connect—I hope these notes make your journey a little easier.