**Welcome to the 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: * [flutter.dev](https://flutter.dev) (main site) * [Installation](https://flutter.dev/docs/get-started/install) * [Codelabs](https://flutter.dev/docs/codelabs) * [Contributing to Flutter](https://github.com/flutter/flutter/blob/master/CONTRIBUTING.md) ### 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).