FlashDevelop:About

FlashDevelop is a free and open source code editor.

Microsoft Windows .NET 2.0 application
Mac OSX/Linux compatible using virtualization software (VirtualBox, VMWare, Parallel)

Do you like cool screenshots? see the Features Tour!

FlashDevelop is open source:

FlashDevelop is a great general purpose code editor:

Easy to use editor with syntax highlighting, bookmarks and tasks (TODO) handling.
Comprehensive Find and Replace Dialog.
Find in Files dialog.
Intuitive and very flexible panel based interface.
Advanced snippet completion (code templates) and integrated snippet editor.
Open plug-in based architecture.

FlashDevelop offers advanced ActionScript coding support:

Supports three languages: ActionScript 2, ActionScript 3 & MXML and HaXe.
Brilliant Actionscript Code Completion (IntelliSense) and code generators.
Code completion for XML, MXML and HTML
Code navigation (jump to declaration), just pressing F4/Shift-F4.
Easy integration with Flash and command line compilers, just using Ctrl+Enter to compile.
Integrated Project Manager to handle all the project assets, properties and files.
Smart project templates to quickly get started.
Instant swf building with MTASC or MXMLC using custom comment tag @mtasc/@mxmlc.
Easy to use Context API search.
Customized GUI for AS2API & ASDocs documentation generators.