Flutter is an open-source UI software development kit (SDK) created by Google. Released in May 2017, it enables developers to build cross-platform applications from a single codebase for various platforms, including Android, iOS, web, desktop (Windows, macOS, Linux), and Fuchsia. Flutter is used internally by Google in apps like Google Pay and Google Earth. The latest stable release, version 3.41, was on February 11, 2026.
Flutter's key features include a single codebase for multiple platforms, hot reload for instant UI updates during development, a rich set of customizable widgets for creating expressive UIs, and high performance due to its compiled language (Dart) and Skia graphics library. It also provides access to native device features and APIs. Flutter is free and open source. While Flutter itself is free, the cost of developing an app with Flutter can range from $10,000 to $200,000 or more, depending on the app's complexity, features, UI/UX design, and the development team's location. Flutter is available as an SDK for Windows, macOS, and Linux.