Flasm is described as 'Free command line assembler/disassembler of Flash ActionScript bytecode. It lets you make changes to any SWF. Flasm fully supports SWFs produced by Macromedia Flash 8 and earlier' and is an app in the development category. There are five alternatives to Flasm for Windows, Linux and Mac. The best Flasm alternative is NASM, which is both free and Open Source. Other great apps like Flasm are Swfdec, SWFTOOLS, SWF Picture Extractor and Flare.
The Netwide Assembler, NASM, is an 80x86 and x86-64 assembler designed for portability and modularity. It supports a range of object file formats, including Linux and *BSD a.out, ELF, COFF, Mach-O, Microsoft 16-bit OBJ, Win32 and Win64. It will also output plain binary files.
SWFTools is a collection of utilities for working with Adobe Flash files (SWF files). The tool collection includes programs for reading SWF files, combining them, and creating them from other content (like images, sound files, videos or sourcecode).
SWF Picture Extractor is a very easy to use software tool designed to help you extract pictures from SWF files, providing a simple interface to lend you a hand in this regard.
Flare processes an SWF and extracts all scripts from it. The output is written to a single text file. Only ActionScript is extracted, no text or images. Flare is freeware. Windows, Mac OS X and Linux versions are available.
