| # Flutter API reference documentation | |
| Flutter is Google's SDK for crafting beautiful, fast user experiences for | |
| mobile, web, and desktop from a single codebase. Flutter works with existing | |
| code, is used by developers and organizations around the world, and is free | |
| and open source. | |
| This API reference covers all libraries that are exported by the Flutter | |
| SDK. | |
| ## More Documentation | |
| This site hosts Flutter's API documentation. Other documentation can be found at | |
| the following locations: | |
| * [Install Flutter](https://docs.flutter.dev/get-started) | |
| * [Flutter documentation](https://docs.flutter.dev) | |
| * [Stable channel API reference documentation](https://api.flutter.dev) | |
| * [Main channel API reference documentation](https://main-api.flutter.dev) | |
| * [Contributing to Flutter](https://github.com/flutter/flutter/blob/main/CONTRIBUTING.md) | |
| ## Offline Documentation | |
| In addition to the online sites above, Flutter's documentation can be downloaded | |
| as an HTML documentation ZIP file for use when offline or when you have a poor | |
| internet connection. | |
| > [!NOTE] | |
| > The offline documentation files are quite large, approximately 300MB zipped, 1GB unzipped. | |
| Offline HTML documentation ZIP bundles: | |
| * [Stable channel](https://api.flutter.dev/offline/flutter.docs.zip) | |
| * [Main channel](https://main-api.flutter.dev/offline/flutter.docs.zip) | |
| Or, you can add Flutter to the open-source [Zeal](https://zealdocs.org/) app | |
| using the following XML configurations. Follow the instructions in the | |
| application for adding a feed. | |
| * Stable channel Zeal XML configuration URL: | |
| <https://api.flutter.dev/offline/flutter.xml> | |
| * Main channel Zeal XML configuration URL: | |
| <https://main-api.flutter.dev/offline/flutter.xml> | |
| ## Importing a Library | |
| ### Framework Libraries | |
| Libraries in the "Libraries" section below (or in the left navigation) are part | |
| of the core Flutter framework and are imported using | |
| `'package:flutter/<library>.dart'`, like so: | |
| ```dart | |
| import 'package:flutter/material.dart'; | |
| import 'package:flutter/services.dart'; | |
| ``` | |
| ### Dart Libraries | |
| Libraries in the "Dart" section exist in the `dart:` namespace and are imported | |
| using `'dart:<library>'`, like so: | |
| ```dart | |
| import 'dart:async'; | |
| import 'dart:ui'; | |
| ``` | |
| Except for `'dart:core'`, you must import a Dart library before you can use it. | |
| ### Supporting Libraries | |
| Libraries in other sections are supporting libraries that ship with Flutter. | |
| They are organized by package and are imported using | |
| `'package:<package>/<library>.dart'`, like so: | |
| ```dart | |
| import 'package:flutter_test/flutter_test.dart'; | |
| import 'package:file/local.dart'; | |
| ``` | |
| ## Packages on pub.dev | |
| Flutter has a rich ecosystem of packages that have been contributed by the | |
| Flutter team and the broader open source community to a central repository. | |
| Among the thousands of packages, you'll find support for Firebase, Google | |
| Fonts, hardware services like Bluetooth and camera, new widgets and | |
| animations, and integration with other popular web services. You can browse | |
| those packages at [pub.dev](https://pub.dev). |