My favorite product for seeing how my Flash/SWF files have been put together is the easy-to-use Nemo 440. Other tools for determining SWF content include swfextract, abcdump, and Flare. These include Flash Decompiler, Flash Decompiler Gold, and Sothink SWF Decompiler. There are also other Flash decompilers, including commercial products. The flash-decompiler project, hosted on Google Code, is intended to be used to decompile Flash files. Note that the swfdump executable is also available with the OpenLaszlo distribution in the same directory (WEB-INF/bin) as other Flex-specific commands such as mxmlc and asdoc. In Disassembling a SWF with swfdump, Gordon Smith outlines how to use the open source Flex SDK download and its swfdump executable tool based on the provided swfutils.jar.

I'll briefly summarize some of them here and provide a little additional detail on my preferred tool: Nemo 440. There are several tools that can help with this. There are times when it is helpful to see the contents of a generated SWF to better understand what is being included in it.

Swf decompiler open source