I hear conflicting comments about Flex being 'free'. What is the straight story on Flex? Is it proprietary?
Well, there is the standard Free as in Beer vs Free as in Speech issue. Flex is Free as in speech (since it is under the MPL), and is Free as in Beer.
Use FlashDevelop for a free IDE. http://www.flashdevelop.org/wikidocs/index.php?title=Features:Interface
I guess one good alternative that is totally free is http://www.openlaszlo.org/ I have played with it in the past and the support is very good too.
I have not used flex because I didn't know it was free. Then again it was a few years since I looked at the area.
The Flex SDK is free. This allows you to compile and debug your Flex app from the command-line.
If you want something more advanced for development, Adobe sells an Eclipse plug-in or Flexbuilder (a custom version of Eclipse), but like most developer tools, and stuff from Adobe, it's pricey.
Oops:Turns out portions of Flex are open source, and available from Adobe.
Flex is a framework based on Actionscript 3.0 and flash platform and you can download the sdk for free here: http://www.adobe.com/products/flex/flexdownloads/#sdk
The issue of cost comes into play if you want to use Flex Builder, which is an IDE for flex development. You can get a free trial of Flex Builder 3.0 for 60 days i believe.
PS Flex is open source... http://opensource.adobe.com/wiki/display/flexsdk/Flex+SDK
FlexBuilder costs $249 for the standard version, which you can download for free for 60 days. The professional version is $699.
Flex itself is free. You could do all of your Flex development in your favorite text editor, without the visual layout and interactive debugging tools that FlexBuilder gives you, and run mxmlc from a build script to compile your code.
The Flex SDK is free and open source.
http://opensource.adobe.com/wiki/display/flexsdk/Flex+SDK
It includes command line tools for compiling Flex and ActionScript based applications.
Adobe sells an Eclipse based IDE named Flex Builder, although this is not required for Flex development.
mike chambers