Google has released version 1.0 of its open-source, cross-platform app building toolkit Flutter, with plans to bring the platform to the web as well. 

Announced earlier today during Flutter Live, Google's conference dedicated entirely to the toolkit, it allows developers to share a single code base across Android and iOS apps, and enables cross-platform app code by working around the UI frameworks of both Android and iOS.

Apps built with Flutter run on the Flutter rendering engine and Flutter framework, which are shipped with every app. It's similar to how a game engine like Unreal or Unity packages its engines in with a game, allowing it to run on different platforms.

Particularly useful for devs, the Flutter SDK offers features like the hot reload, which instantly makes code changes show up in the emulator. 

Additionally, apps come with their own Flutter UI widgets for Android and iOS, with both following their respective widget guidelines.

There's an app showcase which provides a better idea of what can be built using the toolkit, and interested developers can check it out here.