Node.js --env-file: Native .env Support Without dotenv

Problem

Every Node.js project starts with npm install dotenv and a require('dotenv').config() call at the entry point. It works, but it’s yet another runtime dependency that reads and parses a file on startup.

Solution

Node.js 20.6+ ships with a native --env-file flag.

# Basic usage
node --env-file=.env app.js

# Multiple files
node --env-file=.env --env-file=.env.local app.js

The .env file format is the same as before:

DATABASE_URL=postgresql://localhost:5432/mydb
API_KEY=sk-1234567890
NODE_ENV=development

Access variables through process.env as usual — no imports needed.

// No dotenv import required
const dbUrl = process.env.DATABASE_URL;
console.log(dbUrl); // postgresql://localhost:5432/mydb

Node.js 20.12+ also supports programmatic loading:

// Load dynamically at runtime
process.loadEnvFile('.env');

// Parse env string directly
const { parseEnv } = require('node:util');
const vars = parseEnv('KEY=value\nFOO=bar');
console.log(vars.KEY); // "value"

Your package.json scripts get cleaner too:

{
  "scripts": {
    "dev": "node --env-file=.env --watch app.js",
    "prod": "node --env-file=.env.production app.js"
  }
}

Key Points

• Node.js 20.6+ --env-file flag loads .env files natively
• No dotenv package or require call needed
• 20.12+ adds process.loadEnvFile() for dynamic loading
• Multiple env files can be chained; later files override earlier ones
• Projects on Node.js < 20 still need dotenv