JPEXS Free Flash Decompiler is an open source tool for decompiling Flash SWF files, extracting, editing or replacing their contents.
At a minimum you might use the program to grab images, videos or music from an SWF.
You could also tweak an applet, perhaps replacing a background image or the soundtrack. Flash developers might explore scripts to better understand how an applet works, or security experts can analyse a malicious applet to figure out what it's doing.
Whatever you're doing, the program is reasonably easy to use. There's no installation, and it's Java-based, so works almost anywhere: just open your applet and its various resources are displayed in a tree: shapes, sprites, buttons, fonts, frames, scripts and more. Expand a section like Sounds, then browse their contents, and right-click an item to view, remove, replace, export it and more.
JPEXS Free Flash Decompiler has plenty of other higher level functions. If you can't find an SWF file, it's able to search your browser cache, or even its RAM. And whatever you locate may be exported as a stand-alone EXE file, for easy playing on the Windows desktop.
Version 9.0 brings (Changelog):
Instance metadata (AMF3) editing in PlaceObject4
Issue #1162 improved opening loaded SWF files
Issue #1156 Flash Viewer - DefineScalingGrid support (9-slice scaling)
Flash Viewer - skip frames when not on time
Issue #1171 Export stroke scale to FLA
FLA export - check invalid unicode characters
Issue #1199 Automatically import alpha channel to JPEG3/4 from PNG
Issue #1170 Extract from memory in commandline
Reload one vs Reload all buttons
ABC: Float and Float4 support
AS3 p-code instruction documentation in GUI
Issue #1241 Settings to show original bytes in hex view
Search in dump view
Jump to resources view from hex view
Show warning on 32bit JRE
JPEXS Free Flash Decompiler is a powerful application with a stack of essential features, yet remains accessible - and very useable - to non-developers.