.env.development Jun 2026

PORT=5173 VITE_API_URL=http://localhost:3000 DEBUG=true LOG_LEVEL=verbose SECRET_KEY=dev-super-secret-do-not-use-in-prod

Most modern build tools and frameworks (like Vite, Next.js, Create React App, and Nuxt) look for multiple .env files and load them according to a specific hierarchy or priority order.

# .env.development # Public (client-accessible) NEXT_PUBLIC_APP_NAME=MyApp Dev NEXT_PUBLIC_API_BASE=http://localhost:3000/api

In the modern landscape of software development, applications rarely run in a single environment. Code moves from a developer’s local machine to a testing server, and finally to production. Each of these stages requires different configurations—different database credentials, API keys, and debug settings. One of the most effective tools for managing these variations is the environment file. Specifically, the .env.development file serves as the blueprint for your application while you are building it. .env.development

In the past, developers often hardcoded environment variables directly into their code or configuration files. This approach has several drawbacks:

: In your project's root directory, create a new file named exactly .env.development . Define Variables : Add your keys in a KEY=VALUE format.

Regardless of your programming language, environment files follow a rigid structure descended from basic Unix Shell syntax. Valid Formatting Examples 3. Node.js (Express

# .env.development NEXT_PUBLIC_ANALYTICS_ID="UA-DEV-12345" # Available everywhere STRIPE_SECRET_KEY="sk_test_123" # Server-side only Use code with caution. In your code, access them via the standard Node.js syntax: javascript const analyticsId = process.env.NEXT_PUBLIC_ANALYTICS_ID; Use code with caution. 3. Node.js (Express, Fastify) with dotenv

To get the most out of .env.development , follow these best practices:

Many developers forget that frontend frameworks (React, Vue) bake environment variables at build time. If you run npm run build with NODE_ENV=development , your production bundle will contain dev API URLs. Always ensure your build pipeline uses .env.production . Regardless of your programming language

Your test runner (Jest, Mocha, PyTest) should automatically load .env.test and load .env.development .

Based on the benefits and best practices outlined in this paper, we recommend the following:

: For development mode ( npm start ), files load in the following order of priority: .env.development.local (highest priority) → .env.development → .env.local → .env (lowest priority).

: When your application automatically loads different configurations based on the current environment, you never have to worry about a development build accidentally pointing to a production database—a mistake that has caused countless real-world incidents.