Installing Express

Express is published as an npm package, so installing it is a single command once you have a Node.js project in place. The whole setup — from an empty folder to a project ready for its first route — takes about a minute. This page walks through the Node and npm prerequisites, initializing a project with npm init, installing Express, choosing between Express 4 and the newer Express 5, and wiring up the package.json scripts you’ll run every day.

Prerequisites: Node.js and npm

Express runs on Node.js, the JavaScript runtime, and is installed with npm, the package manager that ships alongside Node. You don’t install Express globally or use a special CLI — it lives in each project’s node_modules folder. Express 4 supports Node 0.10 and up, but for any new project you should target a current LTS (Long-Term Support) release. As of mid-2026 that means Node 20 or 22; Express 5 officially requires Node 18 or newer.

Confirm both tools are available and recent before you start:

node -v
npm -v

Output:

v22.14.0
10.9.2

If node isn’t found, or the version is below 18, install the latest LTS build from nodejs.org, or manage multiple versions with a tool like nvm. The npm commands below also work unchanged with pnpm and yarn if you prefer them.

Tip: Always pick an even-numbered LTS release (20, 22, …) for servers. The odd-numbered “Current” lines get the newest features but a much shorter support window, which is rarely what you want in production.

Initializing a Node project

A project needs a package.json — the manifest that records your dependencies and scripts. Create a folder, move into it, and run npm init. The -y flag accepts all defaults and writes the file immediately:

mkdir my-app
cd my-app
npm init -y

Output:

Wrote to /home/you/my-app/package.json:

{
  "name": "my-app",
  "version": "1.0.0",
  "main": "index.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "license": "ISC"
}

Drop the -y if you’d rather answer the prompts interactively and set the name, version, entry point, and license yourself.

Installing Express

With a package.json in place, add Express as a dependency:

npm install express

This downloads Express and its dependency tree into node_modules, records the package under "dependencies" in package.json, and writes a package-lock.json that pins exact versions. By default npm installs the latest stable release. To control which major version you get, name it explicitly:

npm install express@4      # latest 4.x
npm install express@5      # latest 5.x
npm install express@latest # newest published release

After installing, your package.json will show the dependency with a caret range that allows compatible minor and patch updates:

{
  "name": "my-app",
  "version": "1.0.0",
  "main": "index.js",
  "scripts": {
    "start": "node index.js",
    "dev": "node --watch index.js"
  },
  "dependencies": {
    "express": "^4.21.2"
  }
}

Choosing Express 4 vs Express 5

Express 5 became the default latest release in 2025. It is a mostly backward-compatible upgrade with a smaller dependency tree and modern internals, but a few breaking changes mean you should choose deliberately for each project.

Concern	Express 4	Express 5
Minimum Node	0.10+	18+
Async errors	Must call next(err) manually	Rejected promises forwarded to error handlers automatically
Path matching	path-to-regexp 0.x	path-to-regexp 8.x — * and optional params changed syntax
Removed helpers	app.del, res.json(status, obj) available	Legacy signatures removed
Maturity	Battle-tested, vast ecosystem	Modern, recommended for new apps

For a brand-new project, start on Express 5 to get automatic async error handling and a lighter install. For an existing codebase or one leaning on older middleware, Express 4 remains fully supported and is the safest choice until you can test the upgrade.

Warning: In Express 5 the route-matching syntax changed. A catch-all like app.get('*', ...) from Express 4 must be written app.get('/*splat', ...) (a named wildcard) in Express 5. Audit your wildcard and optional-parameter routes when upgrading.

Setting up package.json scripts

The scripts field defines shortcuts you run with npm run <name> (start and test work without run). At minimum, add a start script to launch your server and a dev script for local development. Node 18+ includes a built-in --watch flag that restarts on file changes, so you no longer need nodemon for a simple loop:

{
  "scripts": {
    "start": "node index.js",
    "dev": "node --watch index.js",
    "test": "node --test"
  }
}

Run the dev server like this:

npm run dev

Output:

Server listening on http://localhost:3000

If you prefer the popular nodemon watcher for its richer config, install it as a dev dependency so it doesn’t ship to production:

npm install --save-dev nodemon

Then point your dev script at nodemon index.js.

Verifying the install

A quick sanity check confirms Express resolves correctly before you write real routes:

node -e "console.log('express', require('express/package.json').version)"

Output:

express 4.21.2

Seeing a version number means Express is installed and importable. From here you’re ready to create your first server.

Best Practices

• Target a current Node.js LTS release (20 or 22) and keep it updated to receive security patches.
• Commit package-lock.json so teammates and CI install byte-for-byte identical dependency trees.
• Pin the Express major version (express@4 or express@5) intentionally rather than relying on whatever latest resolves to today.
• Install development-only tools such as nodemon with --save-dev to keep production installs lean.
• Use the built-in node --watch for simple auto-reload before reaching for extra dependencies.
• Add a .gitignore that excludes node_modules/ — it is rebuilt from the lockfile on every install.
• Prefer Express 5 for new projects to get automatic async error handling, but verify wildcard routes when migrating from Express 4.

Related Topics

• Introduction to Express
• Your first Hello World app
• Project structure
• Express 4 vs 5