Adobe Flash Builder 4

Adobe Flash Builder 4 (formerly Adobe Flex Builder) software is designed to help software developers rapidly develop cross-platform rich Internet applications (RIAs) and content using the open source Flex framework.

It includes support for intelligent coding, debugging, and visual design and features powerful testing tools that speed up development and lead to higher performing applications.
Flash Builder 4 includes the complete Flex framework, including compilers, component library, and debuggers.