How to Use .env Files in React with TypeScript: A Complete Guide (2026)

Environment variables are a fundamental part of configuring applications. They allow you to store configuration settings outside your code, providing a way to easily switch environments and manage sensitive information like API keys. In a React project using TypeScript, you might encounter issues when trying to use environment variables, but with the right setup, it's quite straightforward.

Key Takeaways

• Understand the role of .env files in configuration management.
• Learn how to properly configure environment variables in a React project using TypeScript.
• Explore common pitfalls and how to troubleshoot issues.
• Ensure environment variables are correctly typed in TypeScript.

Introduction

In this tutorial, you will learn how to effectively use .env files in a React project that utilizes TypeScript. Environment variables are crucial for managing configuration settings in different environments, such as development, testing, and production. Without proper configuration, environment variables may not work as expected in TypeScript projects.

We will address common issues faced by developers when integrating .env files, such as incorrect variable access and TypeScript type errors, ensuring that you can seamlessly use environment variables in your React TypeScript projects.

Prerequisites

• Basic understanding of React and TypeScript.
• Node.js and npm installed on your machine.
• Familiarity with environment variables and configuration management.

Step 1: Setting Up Your React and TypeScript Environment

First, ensure that you have a React project set up with TypeScript. If you haven't, you can create one using Create React App:

npx create-react-app my-app --template typescript

This command will create a new React project named my-app with TypeScript support.

Step 2: Creating the .env File

Create a file named .env in the root of your project directory. This file will contain your environment variables. For example:

REACT_APP_API_URL="https://api.example.com"

It's important to prefix your environment variables with REACT_APP_, as Create React App will only expose variables with this prefix to the browser.

Step 3: Accessing Environment Variables in TypeScript

Accessing environment variables in your TypeScript code is straightforward. You can use the process.env object:

const apiUrl: string = process.env.REACT_APP_API_URL || "";

To avoid TypeScript errors, you might need to define the types for these environment variables by extending the NodeJS.ProcessEnv interface:

declare global {
  namespace NodeJS {
    interface ProcessEnv {
      REACT_APP_API_URL: string;
    }
  }
}

This ensures that TypeScript recognizes the environment variables and their types, preventing potential runtime errors.

Step 4: Using Environment Variables in Your Application

Once you've set up the .env file and defined types, you can use these variables throughout your application. For example, you might use the API URL in a service file:

export const fetchUserData = async () => {
  const response = await fetch(`${process.env.REACT_APP_API_URL}/users`);
  return response.json();
};

By externalizing these configurations, you can easily switch between different API endpoints for development, testing, and production.

Common Errors/Troubleshooting

• Environment Variables Not Recognized: Ensure that you restart your development server after adding or modifying .env files, as changes are not picked up dynamically.
• TypeScript Errors: If TypeScript complains about missing environment variables, make sure you've extended the NodeJS.ProcessEnv interface correctly.
• Variables Not Accessible: Double-check that your variables start with REACT_APP_. Create React App filters out any variables not following this convention.

Conclusion

Properly managing environment variables in a React TypeScript project is crucial for maintaining clean, scalable, and secure applications. By following this guide, you should be able to configure and use .env files effectively, ensuring that your application is adaptable to any environment.

Frequently Asked Questions

Why do I need to prefix environment variables with REACT_APP_?

Create React App only exposes environment variables that are prefixed with REACT_APP_ for security reasons, ensuring that sensitive information is not accidentally leaked to the client-side.

How do I update environment variables without restarting the server?

Unfortunately, changes to .env files require a server restart to take effect, as the variables are read at startup.

What should I do if TypeScript doesn't recognize my environment variables?

Ensure you've extended the NodeJS.ProcessEnv interface in your TypeScript configuration to include your environment variables with the correct types.