What is an NPM package?

An NPM package is a reusable chunk of JavaScript code that someone has packaged up and published so other developers can use it in their projects. Most NPM packages are libraries, tools you pull into your project to handle a specific job.

NPM stands for Node Package Manager. It’s the default package manager for JavaScript and comes bundled with Node.js. When you run npm install react, you’re downloading the React NPM package and adding it to your project. NPM handles finding it, downloading it, and keeping track of which version you’re using.

There are hundreds of thousands of packages on the NPM registry. They cover almost anything you’d want to do in JavaScript, from date formatting and HTTP requests to testing utilities and UI components. Before reaching for a package, it’s worth checking how many weekly downloads it has and when it was last updated. A package that hasn’t been touched in years and has no active maintainers can become a liability.

Packages are listed in your project’s package.json file, which tracks everything your project depends on. Running npm install reads that file and downloads all the listed packages into a node_modules folder.

I’ve been doing front-end and back-end JavaScript for the past decade, so I’ve used NPM extensively. Other tools have come along over the years, like Yarn and pnpm, but these days I love a vanilla NPM setup with simple NPM scripts. It’s straightforward, well-supported, and doesn’t add extra complexity. And NPM has grown well beyond just web dependencies. Even Claude Code ships as an NPM package.