Adobe has announced that they’re transitioning Flex into Open Source through the rest of 2007. The Flex software development kit (SDK) is used to create applications that can run in any browser with Adobe Flash Player, or as a desktop application with Adobe Apollo.

Adobe isn’t releasing source code for the Flash IDE (“integrated development environment,” the part that we use to interactively create Flash content), or the Flash Player itself. However, most of the other development tools will be available for modification and reuse in applications in ways that haven’t been available before:

Using the MPL [Mozilla Public License] for open sourcing Flex will allow full and free access to source code. Developers will be able to freely download, extend, and contribute to the source code for the Flex compiler, components and application framework.

The ActionScript components of the Flex SDK are already available in source code form, but Adobe will also open source “the Java source code for the ActionScript and MXML compilers, the ActionScript debugger, and the core ActionScript libraries from the SDK.”

The transition to open source will begin this summer, but isn’t expected to be complete until the end of the year.

(Thanks again, Eric Skogen.)

See also Flex: Open Source