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:

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:

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:

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:

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.

Libraries

animation
The Flutter animation system. [...]
cupertino
Flutter widgets implementing the current iOS design language. [...]
foundation
Core Flutter framework primitives. [...]
gestures
The Flutter gesture recognizers. [...]
material
Flutter widgets implementing Material Design. [...]
painting
The Flutter painting library. [...]
physics
Simple one-dimensional physics simulations, such as springs, friction, and gravity, for use in user interface animations. [...]
rendering
The Flutter rendering tree. [...]
scheduler
The Flutter Scheduler library. [...]
semantics
The Flutter semantics package. [...]
services
Platform services exposed to Flutter apps. [...]
widgets
The Flutter widgets framework. [...]

Dart

dart:ui
Built-in types and core primitives for a Flutter application. [...]

Core

dart:async
Support for asynchronous programming, with classes such as Future and Stream. [...]
dart:collection
Classes and utilities that supplement the collection support in dart:core. [...]
dart:convert
Encoders and decoders for converting between different data representations, including JSON and UTF-8. [...]
dart:core
Built-in types, collections, and other core functionality for every Dart program. [...]
dart:developer
Interact with developer tools such as the debugger and inspector. [...]
dart:math
Mathematical constants and functions, plus a random number generator. [...]
dart:typed_data
Lists that efficiently handle fixed sized data (for example, unsigned 8 byte integers) and SIMD numeric types. [...]

VM

dart:ffi
Foreign Function Interface for interoperability with the C programming language. [...]
dart:io
File, socket, HTTP, and other I/O support for non-web applications. [...]
dart:isolate
Concurrent programming using isolates: independent workers that are similar to threads but don't share memory, communicating only via messages. [...]

Web

dart:html
HTML elements and other resources for web-based applications that need to interact with the browser and the DOM (Document Object Model). [...]
dart:js
Low-level support for interoperating with JavaScript. [...]
dart:js_util
Utility methods to manipulate package:js annotated JavaScript interop objects in cases where the name to call is not known at runtime. [...]

platform_integration

Android
Flutter platform integration APIs for Android.
iOS
Flutter platform integration APIs for iOS.

flutter_test

flutter_test
Testing library for flutter, built on top of package:test. [...]

flutter_driver

flutter_driver
Provides API to test Flutter applications that run on real devices and emulators. [...]
flutter_driver_extension
This library provides a Dart VM service extension that is required for tests that use package:flutter_driver to drive applications from a separate process, similar to Selenium (web), Espresso (Android) and UI Automation (iOS). [...]

flutter_localizations

flutter_localizations
Localizations for the Flutter library

flutter_web_plugins

flutter_web_plugins

archive

archive
archive_io

async

async

boolean_selector

boolean_selector

characters

characters
String operations based on characters (Unicode grapheme clusters).

charcode

charcode
Defines symbolic names for character code points. [...]
charcode.ascii.dollar_lowercase
Declare integer constants for each ASCII character. [...]
charcode.htmlentity.dollar_lowercase
Character codes based on HTML 4.01 character entity names. [...]

clock

clock

collection

collection
dart.pkg.collection.algorithms
Import collection.dart instead.
dart.pkg.collection.equality
Import collection.dart instead.
dart.pkg.collection.iterable_zip
Import collection.dart instead.
dart.pkg.collection.priority_queue
Import collection.dart instead.
dart.pkg.collection.wrappers
Import collection.dart instead.

convert

convert

crypto

crypto

fake_async

fake_async

file

chroot
file
local
memory
record_replay

intl

date_symbol_data_custom
date_symbol_data_file
This file should be imported, along with date_format.dart in order to read locale data from files in the file system.
date_symbol_data_http_request
This file should be imported, along with date_format.dart in order to read locale data via http requests to a web server..
date_symbol_data_local
Date/time formatting symbols for all locales. [...]
date_symbols
date_time_patterns
Date/time formatting symbols for a large subset of locales. [...]
intl
This library provides internationalization and localization. This includes message formatting and replacement, date and number formatting and parsing, and utilities for working with Bidirectional text. [...]
intl_standalone
This provides facilities for Internationalization that are only available when running standalone. You should import only one of this or intl_browser.dart. Right now the only thing provided here is finding the operating system locale.
locale
message_format
MessageFormat is a "locale aware printf", with plural / gender support. [...]
message_lookup_by_library
Message/plural format library with locale support. This can have different implementations based on the mechanism for finding the localized versions of messages. This version expects them to be in a library named e.g. 'messages_en_US'. The prefix is set in the "initializeMessages" call, which must be made for a locale before any lookups can be done. [...]
number_symbol_data
Date/time formatting symbols for all locales. [...]
number_symbols

json_rpc_2

error_code
json_rpc_2

matcher

matcher

meta

meta
Constants for use in metadata annotations. [...]
meta_dart2js
Constants for use in metadata annotations to provide hints to dart2js. [...]

path

path

platform

platform

process

process
record_replay

pub_semver

pub_semver

source_span

source_span

stack_trace

stack_trace

stream_channel

isolate_channel
stream_channel

string_scanner

string_scanner

sync_http

sync.http

term_glyph

term_glyph

test_api

test_api
test_api.backend

typed_data

typed_data
Utilities and functionality related to the "dart:typed_data" library.
typed_data.typed_buffers
Growable typed-data lists. [...]

vector_math

hash
vector_math
A library containing different type of vector operations for use in games, simulations, or rendering. [...]
vector_math_64
A library containing different type of vector operations for use in games, simulations, or rendering. [...]
vector_math_geometry
A library containing geometry generators (like CubeGenerator, SphereGenerator and CylinderGenerator) and filters (BarycentricFilter, ColorFilter and InvertFilter).
vector_math_lists
A library for working with lists of vectors in a memory efficient way.
vector_math_operations
A library containing matrix operations (Matrix44Operations) that can be performed on Float32List instances and SIMD optimized operations (Matrix44SIMDOperations) that can be performed on Float32x4List instances.

web_socket_channel

web_socket_channel
web_socket_channel.io
web_socket_channel.status
Status codes that are defined in the WebSocket spec. [...]

webdriver

webdriver.core
webdriver.core
webdriver.html
webdriver.io
webdriver.io
webdriver.support.async
webdriver.support.firefox_profile
webdriver.support.forwarder
webdriver.support.stdio_stepper
webdriver.sync_core
webdriver.sync_io