Efficiently Configuring Your Flutter App with — dart-define-from-file

3 min readMar 23


Building a Flutter app requires the use of environment variables to configure various aspects of the app, such as API keys, endpoints, and other sensitive information. Traditionally, developers have relied on tools such as env and dotenv to manage their environment variables in Flutter apps. However, these methods can be cumbersome and potentially insecure, as they require manually updating the variables and storing sensitive data in plain text.

In this article, we will explore an alternative approach to loading environment variables in Flutter apps using the --dart-define-from-file flag. This method allows you to define your environment variables in a separate configuration file, which can be easily updated and secured without compromising sensitive data. By the end of this article, you will have a step-by-step tutorial on how to implement the --dart-define-from-file flag in your Flutter app and take advantage of its benefits over traditional methods.

Environment variables are essential for configuring apps without hard-coding values into the source code. Traditionally, Flutter developers use env and dotenv to manage environment variables. However, these methods have limitations and potential security risks. The --dart-define-from-file flag provides an alternative approach that allows developers to load environment variables from a configuration file, which can be easily managed and secured without third-party packages or manual updates. In the next section, we will explore how to use this flag to configure your Flutter app.

Example of Config File

Now you create your config.json file where you save all your environment variable,Now that we have created a configuration file and set up our Flutter app to use the --dart-define-from-file flag, we can add our environment variables to the app.

In your Flutter code, you can access the environment variables using the variable name defined in your configuration file. For example, if you have defined an environment variable named API_KEY and RELEASE_VERSION in your configuration file, you can access it in your code like this:

Note that the variable name in fromEnvironment is case-sensitive and must match the name in your configuration file.

By using the --dart-define-from-file flag, you can easily manage and update your environment variables without the need for third-party packages or manual updates to your .env file. Additionally, this method provides an extra layer of security by allowing you to keep sensitive data out of your source code and in a separate, secure configuration file.

Instead of relying on flutter run --dart-define-from-file=/filepath/config.json to run or build your app, you can streamline the process by setting up your launch.json file in VSCode. This allows you to build your app with a single click of the 'Run' button, making your development workflow even more efficient. Here's an example of how you can configure your launch.json file to use the --dart-define-from-file flag:

Make sure to replace /filepath/config.json with the actual file path of your configuration file in your local directory."

As you continue to develop your Flutter app, consider using the --dart-define-from-file flag to manage your environment variables and improve your app's security and efficiency.




I'm a Mobile Developer (Flutter) , Interested In science and how it's suppose to help.