

1. Adobe Flex Builder 3
Flex Builder 3 is the biggest tool available for a Flex developer’s tool kit. Armed with an array of features that can speed up the development, the inherent debugger, the memory profiler, and the performance profiler are especially valuable for debugging and improving your applications.
It is not free, but worth a buy. Try the trial version first.
2. fdb
% cd $FLEX_INSTALL_DIR/bin
% fdb
You’ve started the Flex command-line debugger now. Use the ‘help’ and ‘tutorial’ commands and explore further. It has useful features, is easy to learn, and quick to use.
3. FlexLib
The FlexLib project is a huge effort to create open source user interface components for Adobe Flex 2 and 3. The repository currently has over twenty components that come under packages like charts, containers, controls, mdi, scheduling, skins. The project is extensively documented.
Note: flexmdi, a robust, extensible Multiple Document Interface framework for Adobe Flex was previously a separate project that is now under FlexLib. It has its own tutorials in its project page.
4. Flex-Spy
Flex-Spy is a simple tool that can be used to inspect, monitor, and dynamically change most properties and styles of the visual components in your Flex application.
Check this cool demo of Flex-Spy; it takes less than a minute to understand how to use it.
5. Mate
Mate is a tag-based, event-driven Flex framework that has been lauded for its simplicity and unobtrusiveness. The framework is very well-documented. When you visit their site, do check out the examples and extensions.
6. OpenFlux
OpenFlux is an ambitious open source component framework that allows developers to create radically new and custom Flex components. The underlying principle is that each component is defined using three core parts: API, graphics, behavior (Model-View-Controller framework). Find out more about the project from one of the project owners himself.
7. ReflexUtil
This is an open source utility that allows Flex developers to debug and alter properties of components while running an application. Unsurprising for a light tool, it is very easy to use. The latest version was released about two months ago.
8. Slide
Slide is a Flex framework that uses familiar design patterns, MVC structure, and incorporates debugging and development tools in it. It has not yet been released, but its lists of key features and benefits are impressive enough to warrant attention.
9. ThunderBolt
ThunderBolt is a logger extension for Flash ActionScript 2 and 3 as well as Flex 2 and 3 applications based on the Firebug add-on for Firefox. Read the post Debugging Flex With ThunderBolt to know more about it.
10. XMLObjectOutput
Flex’s undocumented utility called XMLObjectOutput logs simple string data to the flashlog.txt by tracing the values and attributes of XML objects, arrays and other ActionScript objects. It converts XML Objects to simple object types. Read this Flex Article on Adobe to learn about client-side code debugging in Flex applications using XMLObjectOutput.
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Just because a project is hosted on GoogleCode, doesn’t mean it’s a “Google’s open source project”.
Thank you for pointing that out, Fez. Makes sense.
Thanks for this list of great components.
I wish to add in it KapInspect, this new free Flex debugging, introspection and inspection tool.
Somehow similar to FlexSpy (it even integrates FlexSpy’s excellent stylesheet editor), it allows the developer to dynamically inspect all data of its application, drilling-down into classes as in the Flex debugger windows (except for private vars)
It also has a powerful EventConsole that allows to trace all standard events on UIComponents and framework objects (timer, ArrayCollection,..)
You will find it here: http://lab.kapit.fr/display/kapinspect/Kap+Inspect
On this site (http://lab.kapit.fr), you will find other free Flex components, mainly for data visualisation: Flex diagrammer component, Graph visualizer with many automatic layouts, Treemap and Radar chart (Kiviat) component
That’s great, Julien. Thank you for the plug.
There is a new debugging tool on the block and this one was designed from the ground up for RIAs. Check out RIA AppPuncher Debugger. A free trial is available at:
http://www.themidnightcoders.com/products/ria-apppuncher/overview.html
Application siblings for things like…load testing…will be available very soon.
Cheers,
Kathleen