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This pure Dart, fully tested and and dependency-free package provides functionality for working with HTTP status codes in a functional programming style.


  • Extends num? types (so int included too) with helper functional methods (when, map, maybeWhen, etc.) and boolean getters for handling HTTP status codes.
  • Provides StatusCode enum for easy handling of all IANA registered HTTP status codes and some common unofficial status codes (also in functional style (when, map, maybeWhen, etc.)).
  • Provides methods for parsing HTTP status codes from String and num types, and much more.


Use your favorite HTTP client libraries such as http or dio and take advantage of this package's functional API to easily handle HTTP status codes in your Dart project.

  /// Checks if status code is >=200 & <=299.
  print(105.isSuccess); // Prints false.
  print(200.isSuccess); // Prints true.

  /// Prints true in all those cases.
  print(105.isInformational); // Prints true, when status code is >=100 & <=199.
  print(300.isRedirection); // Prints true, when status code is >=300 & <=399.
  print(404.isClientError); // Prints true, when status code is >=400 & <=499.
  print(501.isServerError); // Prints true, when status code is >=500 & <=599.

  /// Checks if status code is >=100 & <=600.
  print(16.isStatusCode); // Prints false.
  print(160.isStatusCode); // Prints true.

  /// Also with functional style methods like:
  /// - `mapStatusCode`, `maybeMapStatusCode`, `mapToRegisteredStatusCode`,
  /// - `whenStatusCode`, `whenConstStatusCodeOrNull`, `whenConstStatusCode`.
  // Prints 'ok'.
  print(200.maybeMapStatusCode(orElse: (_) => '?', isSuccess: (_) => 'ok'));
  // Prints '?'.
  print(600.whenConstStatusCodeOrNull(isSuccess: () => 'ok') ?? '?');

  /// Any of those `num?` based codes it's possible additionally map to
  /// a registered status code (official and non-official ones).:
  var registeredCode = 160.toRegisteredStatusCode(); // Is null.
  registeredCode = 200.toRegisteredStatusCode(); // Is StatusCode.okHttp200.
  // Handle any type of registered status codes via functional methods:
  return registeredCode?.whenOrNull(
    okHttp200: () => print('ok'),
    // Includes all official IAN codes.
    badRequestHttp400: () => print('oh no!'),
    // Includes common unofficial codes too.
    unauthorizedHttp561: () => print('refresh token'),


You can also play around with this example in the Zapp!


Why should I use this package?

The use of StatusCode enum and boolean getters (isInformational, isSuccess, isClientError, etc.) combined with functional methods (like whenConstStatusCodeOrNull, whenConstStatusCodeOrNull, whenOrNull, etc.) offers several advantages over using hardcoded integer status codes:

  1. Readability: Enums and boolean getters provide a clearer understanding of the code at a glance. response.statusCode.isSuccess is more readable and conveys intent better than response.statusCode >=200 && response.statusCode <=299.

  2. Maintainability: Using enums and methods abstracts the underlying integer values. If the standard changes or you want to update the way you handle status codes, you only have to change the implementation in one place.

  3. Error Prevention: Hardcoded integers can lead to mistakes like typos (e.g., 200 vs. 20). Enums prevent this class of errors and ensure that only valid status codes are used.

  4. Consistency: It's easy to be consistent across a codebase when using a defined set of enums and methods. Different developers on the same team are less likely to use different codes for the same purposes.

  5. Functional Style: The functional methods allow for more expressive code constructs. They enable chaining and passing functions as arguments, leading to more compact and declarative code.

  6. Safety: By using enums and helper methods, you can avoid comparing against undefined or unexpected status codes, which might lead to bugs.

  7. Discoverability: Autocomplete features in IDEs work better with enums and class methods, making it easier for developers to discover and use the functionality provided by the library without having to remember specific numeric codes.

  8. No 3rd-party dependencies: This package has no third-party dependencies, ensuring that you won't have any issues or conflicts with other dependencies (no even meta here, because of that).

  9. High code coverage: The code in this package has a high level of coverage, providing confidence in its reliability and stability.

  10. Industry adopted: This package is actively used in production by numerous European companies, ensuring its efficacy and robustness in real-world scenarios.

  11. BSD-3-Clause License: This package and sources are released under the BSD-3-Clause license, a permissive license that is also used by the Flutter SDK. It allows users to use, modify, and distribute the code with minimal restrictions.

By using these features of the functional_status_codes package, you promote a more robust, readable, and maintainable approach to HTTP status code handling in your Dart projects.

Getting started

To use this package, add functional_status_codes as a dependency in your pubspec.yaml file.

  functional_status_codes: any

Then import the package in your Dart code:

import 'package:functional_status_codes/functional_status_codes.dart';

Additional information

For more information on using this package, check out the API documentation and example.

If you have any issues or suggestions for the package, please file them in the GitHub repository.


This package provides a functional programming style for working with HTTP status codes.