Flutter is Google's open-source framework, or SDK (software development kit), for building apps for mobile, web, desktop and embedded devices from a single codebase. A framework supplies the structure and ready-made parts of an app, so the developer writes only the app's own logic and screens. Flutter is supported by Google and maintained together with a global community of developers.
Flutter apps are written in Dart, a programming language made for fast apps on many platforms. Flutter code compiles to ARM or Intel machine code for phones and desktops, and to JavaScript or WebAssembly for the web. Screens are built from widgets, small reusable interface parts, with ready sets in Apple's iOS style (Cupertino) and Google's Material style; the app controls every pixel, drawn by hardware-accelerated 2D graphics libraries such as Skia and Impeller. Stateful hot reload shows a code change in the running app almost at once, without losing its state. Packages on pub.dev add features, and Flutter connects to Google services such as Firebase, Google Ads and Google Maps.
Flutter is free and open source under the BSD-3-Clause license.