Packages are published to pub.dev.
The Flutter landing page on pub.dev displays top packages that are compatible with Flutter (those that declare dependencies generally compatible with Flutter), and supports searching among all published packages.
The Flutter Favorites page on pub.dev lists the plugins and packages that have been identified as packages you should first consider using when writing your app. For more information on what it means to be a Flutter Favorite, see the Flutter Favorites program.
You can also browse the packages on pub.dev by filtering on Android, iOS, web, Linux, Windows, macOS, or any combination thereof.