Why should you use kReleaseMode instead of assert?

Using kReleaseMode instead of assert is a best practice in Flutter for managing code behavior and optimizations between release and debug modes. Flutter provides the kReleaseMode constant as part of the foundation package, and it is typically used to conditionally enable or disable certain features or behaviors based on the application’s build mode.

Here’s the main reason why you should use kReleaseMode instead of assert:

  1. Build Mode Behavior:
    • assert: The assert statements are only active in debug mode. When you run the app in debug mode (using flutter run without the --release flag), the assert statements are checked, and if any of them evaluate to false, an assertion failure is triggered, leading to an immediate crash. However, in release mode, the assert statements are removed from the code during compilation, and they do not have any effect on the app’s behavior or performance.
    • kReleaseMode: The kReleaseMode constant is true when the app is running in release mode (i.e., when you build the app using flutter run --release or flutter build). It is false when the app is running in debug or profile mode (i.e., when you use flutter run without the --release flag). By using kReleaseMode, you can conditionally execute specific code or enable certain optimizations only in release mode while keeping them disabled in debug mode.

Using kReleaseMode can be especially useful for scenarios like:

  • Disabling logging or debug information in release mode to improve performance and reduce the app’s size.
  • Implementing environment-specific configurations or API endpoints, where you might have different values for debug and release modes.
  • Enabling or disabling certain features that are only intended for development or debugging purposes.


import 'package:flutter/foundation.dart';

void main() {
  // Enable specific features only in release mode.
  if (kReleaseMode) {


In this example, enableAnalytics() will only be called if the app is running in release mode, as determined by the value of kReleaseMode.

In summary, you should use kReleaseMode instead of assert when you want to conditionally enable or disable certain features or optimizations based on the application’s build mode (debug vs. release). This allows you to have different behaviors between debug and release modes, ensuring that your app performs optimally in production while providing helpful debugging information during development.

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