This aims to be a comprehensive list of links to Open Source Flash projects, both those hosted on OSFlash and elsewhere.

Note: This list does not include tools that are not open source. See Closed Source Flash Tools for a list of such tools where an open-source alternative does not exist. The primary focus of this site and community is open source, not free or commercial Flash tools and projects that are not open source. We only list free (and commercial) tools when an open-source alternative does not exist or the tool is nonetheless necessary for a common workflow, possibly involving other open-source tools.

• swift - A comprehensive IDE with full Actionscript support and the ability to export to animated HTML5 as well as Flash Swift home page
• AjaxAnimator - An online, collaborative, web-based animation suite with support for exporting to Flash, Silverlight, GIFs, and more Homepage Live Application
• flashdevelop - A popular open source ActionScript 2/3 and web development environment developed in .Net FlashDevelop Home Page
• OpenDialect (working link) - A Flex based Flash IDE for creating and publishing Flash Movies Open Dialect Home Page (dead link)

• Salasaga - In development eLearning IDE, aiming to be an improvement on Adobe's Captivate. Salasaga Homepage

• MiniBuilder - Flash based IDE for ActionScript MiniBuilder Homepage

• Adobe Flash Player - the official runtime environment available for Windows, Mac and other platforms for MSIE and Firefox (+compatibles) in 32 bit and 64 bit versions
• * Alternative Flash Downloader - a third party helper application for keeping the original flash plug in for multiple browsers up to date
• * Firefox Plugin check - a web page that checks for the most recent version of the flash plug in; works for any flash enabled browser (not only for Firefox), and for several other plugins e.g. Java
• Gnash - flash plugin replacement; free software & open source
• swfdec - flash plugin replacement; free software & open source
• lightspark - flash plugin replacement; free software & open source

Not really a flash replacement but a method to obsolete the need for flash support in certain areas are:

• Grease Monkey scripting with scripts that redirect e.g. YouTube videos to VLC or other media player.
• Donwload extensions for flv (flash video) and MP4 (mpeg 4 videos) that do not need any flash.
• HTML5 compatible browsers that obsolete the need for flash plugins for video playback on YouTube (and maybe other platforms) but instead play back video streams by means of built in native software

• AFLAX - JavaScript development library for Flash. No ActionScript or compiler required.
• MTASC - ActionScript Compiler
• Swfmill - XML to SWF, SWF to XML command line compiler
• FFMPEG - Video transcode engine which also supports FLV
• FLVTool2 - FLV Metadata Updater
• Flasm - Assembler/Disassembler for ActionScript Bytecode
• Ming - Ming is a C library for generating SWF (“Flash”) format movies, plus a set of wrappers for using the library from C++ and popular scripting languages like PHP, Perl, Python, and Ruby.
• Flagstone Transform - Java library that enables you to create SWF files (full SWF 10 Spec.)
• JavaSWF2 - JavaSWF2 is a set of Java packages that enable the parsing, manipulation and generation of the Macromedia Flash(TM) file format known as SWF (“swiff”).
• JSwiff - pure Java framework for Macromedia Flash file creation and manipulation.
• JGenerator - The JGenerator is the web server production application that can dynamically combine text, graphics, and sound to build rich Flash content, and is a free alternative to Macromedia Generator.
• SWF Tools - SWF Tools is a collection of SWF manipulation and creation utilities written by Rainer Böhme and Matthias Kramm. It is released under the GPL.
• FlashCommand - a command line compiler for Flash IDE. Developed by Mike Chambers of Macromedia.
• s2x - Python script for converting .sol to XML and back.
• swcextract - Extract, consolidate, rename and organize intrinsic ActionScript class files and (optionally) component SWFs from SWC files.
• itface - Console AS3 compiler using FlexBuilder alpha.
• RSWF - Rebol script for making and exploring SWF files
• Torta - Torta generates a flash file that shows you how your disk space is being used. Torta is written in Common Lisp.
• EnLarge - ActionScript preprocessing tool that enables the development of a single code base that targets Flash Player (7, 8 and 9), Flash Lite 2 and GNU Gnash.
• vixy.net flv2mpeg4 - FLV to AVI/MP4/MOV command line transcoder
• FleVI - Flex 2.0.1 SDK Visual tool for easy development of Flex / AS 3.0 projects for Flashplayer 9.Supports auto project creation,Application + Component compiler & ASDoc.
• FAR (FlashArchive) - A command line tool for creating ZLIB compressed archives that can be progressively loaded from the Flash player at run-time using the provided ActionScript 3 API.
• xml2swf - C program that converts xml to swf. Builds on Linux/Posix or Windows (using mingw and msys) systems.
• libswf - C++ code to generate SWF files from scratch. According to Sourceforge, code is cross-platform. Was able to get it to compile on Windows with mingw.
• Flexcover - A modified Flex SDK version that instruments code for live measurement of code coverage during execution, including an AIR viewer for statistics and annotated source code. Saves XML reports for fully automated coverage testing.
• flvlib - Python library for dealing with FLV files
• FlashPascal - A free Pascal compiler for Flash.

• Eclipse - The IDE platform
• ASDT - ActionScript Development Tool
• IDE for Laszlo - Wysiwyg editor plugin/IDE for Laszlo
• Flair - A Set of plugins for log and view SWF
• As2 Class Browser - plugin - Accessible through the Eclipse Help Panel
• LiveDocs Browser - Browse MM's LiveDocs through the Eclipse Help Panel
• Colorer-take5 - A syntax-highlighting Eclipse plugin that supports Actionscript
• Ant - Used by Eclipse to automate the building of Flash projects
• J2AS - Java to ActionScript Converter

http://www.sellgw2gold.com

• BBC OSFlash - List of open source Flash projects from the BBC
• CASA Lib - CASA Lib is a flexible ActionScript library designed to streamline common chores and act as a solid, reliable foundation for your projects. It provides a core set of classes, interfaces, and utilities to get you coding faster and more reliably without getting in the way.
• openclasslibrary - An OSFlash hosted collection of Actionscript classes.
• Flash layout managers - Actionscript layout managers.
• FlashVid - Actionscript plugins providing Audio-Video streaming and playback. Designed to be used pre-built in a web site to provide youtube-like or videoconferencing functionality. No modifications - no actionscript programming knowledge - required.
• EventController - Event management made easy. A leak free event experience for AS3
• EventTree - Another way to control event listeners and organize complex event sequences

• ActionStep - Open source component framework project based on NextStep/OpenStep/GNUStep/Cocoa “Application Kit”
• ARP - Pattern-based RIA framework (ActionScript 2) for Flash and Flex.
• As2lib - Open source framework (ActionScript 2) that offers support for event handling, error handling, logging, overloading, reflections, data holders, iterators, unit testing, mock objects, profiling, local connections and file loading (is Flash, Flex, MTASC, FAME, … compatible)
• AS3Commons Collections Framework - The most serious ActionScript collections resource in the web – providing both a sophisticated collections framework as well as a library of fast collection implementations.
• AS3Commons UI - Algorithms and managers to serve common UI releated tasks such as layouting, focus and keyboard management, popup handling, drag and drop control and so on. All packages support native Flash display objects. Usage of UI does not require interface implementations. The first version (0.1.x) includes the sole layout package.
• AS DataProvider Controls library - Set of lightweight standard user interface components. Including ListView, TreeView, SelectBox, Button, ScrollPane, ColorPicker, …
• ASAP Framework - A Flash ActionScript 2.0 RIA library for the development of maintainable, multi-movie, event based interactive applications. Compatible with both MTASC and MMC.
• AsWing - AsWing is an ActionScript Component Framework based on Java Swing.
• Cairngorm - Pattern-based RIA framework (ActionScript 2) for Flex and Flash.
• Digizex - Extremely easy-to-use and customizable AS3 Content Management System (CMS) and integrated debugger for Flash and Flex. Includes SWFAddress integration and out-of-box support for multilingual websites.
• disccollision - An open source collision detection system for Flash ActionScript3 (AS3).
• Edumatic - Actionscript 3 e-learning framework similar to ARP
• EnFlash - ActionScript Application Framework
• Gaia Framework - Gaia is a pragmatic, agile framework for Actionscript 3 and 2, which features a revolutionary scaffolding engine and includes SWFObject and SWFAddress integration.
• gamepackage - Open source ActionScript 2 framework for gamedevelopment(mode7, raycasting, tile2d, pathfinder,…), an audiopackage and lots of useful util and math classes
• GameScroll - Open source ActionScript 2 System|Framework for scroll-gamedevelopment
• GUGGAFF - Pattern-based RIA framework (ActionScript 2) for Flash
• Jakute Styling Engine - CSS styling framework for Flash. Supports independent components, external style sheets, global and inline styles, contextual selectors, states, runtime modifications
• JumpShip Framework - An MVC based ActionScript Framework with A Ruby on Rails design philosophy.
• PushButton Engine - A component-based Flash game framework. Components are modular and add rendering, physics, networking, etc. Core classes provide resource management, logging, debug monitoring, serialization, time management, globally named objects, etc.
• Razor Component Framework - A code-only component framework for Actionscript 2 and 3.
• Log5F - The ActionScript 3.0 Logging Utility for Flash/Flex/AIR applications.

• SWFSEO - An ultralight SEO-friendly scaffolding framework.
• Soma UI - Soma is Flash MVC Framework written in Actionscript 3 that will reduce development time.
• Bojinx Framework - A modular and light weight framework for developing Flex/Pure AS3 and AIR applications which is easy to extend and learn. A blog with forum is also available here.

• AnimationPackage - helps you to create powerful and maintainable animations in an efficient and easy way.
• Flade - a free library for simulating 2D physics in Flash.
• Fuse - Animation packaged which builds on the functionality of MovieClip Tweening Prototypes
• MC Tween - Actionscript tweening extension, used to start transitions and tweens via code on MovieClip, TextField and Sound objects, for both AS1 and AS2. Uses Robert Penner's easing equations.
• Movieclip Tweening Prototypes - ActionScript 2 (and 1) api for tweening with lots of easing equations.
• TweenDark - Lightweight, fast, BSD-licensed Tweening Engine for AS3
• TweenLite - Lightweight, High-Performance Tweening Engine for AS3 and AS2
• wisASLibrary - An ActionScript 2 library with lots of animation math.

• ASTUce - An ECMAScript regression framework based on JUnit
• AsUnit - Unit testing framework for ActionScript 2 (works with Flash, Flex, MTASC, FAME, etc.)
• FlexUnit - Unit testing framework for ActionScript 2.0 (Flex and Flash)
• FlexMonkey - Records and plays back Flex UI interactions and generates FlexUnit test cases.

• ASCrypt - Cryptography classes for Actionscript 2
• AS3 Crypto Library - Cryptography library for as3, with TLS 1.0(SSL 3.1) support, featuring RSA, AES, RC4, MD5, SHA-1, SHA-256 and more. BSD license.
• ASLib - An ActionScript 2.0 based library that implements common data structures.
• BiG - AS2 | FlashRemoting Image Gallery.
• core2 - An ECMAScript library that extend the core objects.
• DENG - DENG is a Flash 6 component written in ActionScript 1 that renders subsets of XHTML, XForms, SVG, XFrames with CSS
• FlashAnt - FlashAnt includes an Apache Ant task for integrating Flash into the build process of Rich Internet Applications.
• Flash JavaScript Integration Kit - Allows you to call JavaScript functions from ActionScript, and vice versa. All major data types can be passed between the two environments, and it works across browsers and platforms.
• Flashr - AS2 wrapper for the flickr.com API.
• f_TEA - 128-bit encryption system for Flash and PHP.
• fosFORO - A Text Formatter that allow you to use emoticons and some other tags.
• FP XHTML Render - XHTML parser and render component for Macromedia Flash 2004 (ActionScript 2.0).
• JSON - JSON (JavaScript Object Notation) is a lightweight data-interchange format, with an open source ActionScript implementation.
• MovieClipLoader6 - Flash player 6 compatible implementation of Flash player 7's MovieClipLoader class.
• OSCLib - Open Sound Control library for AS3.
• OpenSource FLV Player - Embeddable FLV player for Flash Player 8 and 9.
• PanoSalado - Open source 360° panorama viewing engine, based on Papervision.
• Sandy - AS2 3D API
• ScrollAPI - A little framework for quick ScrollBar development
• SMX components set - A component library for Flash MX 2004, built with the MX v2 architecture
• splinklibrary - splinklibrary (as3) features event distribution, queues, reflection, logging (log4j style), tweening (queue based) and loading (queue based)
• we3d - AS2 and AS3 3D Engine
• XIFF - API for the XMPP Instant Messaging protocol
• XPath4AS2 - An XPath library for ActionScript from XFactorStudio.

• silex - Open Source Flash CMS used by designers to produce Flash websites which are
  • SEO friendly
  • multilingual
  • deeplinking enabled
  • for Flash 7, 8 or 9
• Flaxus - Flaxus is a software developed under the TOPLAP manifesto, to perform visual performances in real time.
• FlashMyAdmin - MySQL Administrator application in Flash.
• Xical - A Flash/ActionScript based Open Source Rich Media Framework with a player for presentations and e-learning lektures.
• Big - A Xhtml/Flash Image gallery
• FCMS - a Flash presenter system for phpwcms to allow an HTML and a Flash presentation of the same site data. Uses AMFPHP(currently pre-alpha)
• Open Yaargh!PG - a Online Flash RPG about pirates. Uses AMFPHP
• FTF Flash Text Formatter - Formats the text according to keyword definition list stored in external XML file.
• FlashVid - Actionscript plugins providing Audio-Video streaming and playback. Designed to be used pre-built in a web site to provide youtube-like or videoconferencing functionality. No modifications - no actionscript programming knowledge - required.
• Movie Masher - an AS3-based online video editor made to be skinned and extended with custom effects, transitions and controls. Works with any CGI scripting language.

• FlashBannerOnline - an Online free software to create pro Flash Banner by full customization.

• Red5 - Open Source Flash RTMP Server
• Spark - Java flash server which supports remoting and server side js.
• OpenLaszlo - Open source platform with presentation server similar to Flex
• AMFPHP - Flash Remoting for PHP
• PHPObject - Flash Remoting alternative for PHP
• SabreAMF - AMF Client/Server library for PHP5
• OpenAMF - Flash Remoting for J2EE
• AMF::Perl - Formerly known as Flash::FLAP, AMF::Perl is an Open Source Perl and Python implementation of Macromedia's AMF protocol.
• Oregano - A Multiuser Server written in Java
• Jive Messenger - An XMPP Server written in Java which integrates well with the XIFF library.
• JOnAS - A J2EE Open Source Application Server. This server is Sun Certified since v4.3.4.
• XML-RPC Client - Allows Flash to act as a client to an XML-RPC Service.
• Fluorine - Flash Remoting for .NET.
• flosc - Flash OpenSound Control, a Java server enabling communication between Flash and OSC-enabled applications.
• CakePHP - A Rails-inspired powerful and easy to use PHP framework. Can be used to develop flash app backends as AMFPHP is supported through CakeAMFPHP (see below).
• CakeAMFPHP - Adapter classes to make AMFPHP work seamlessly with CakePHP. This way, you can leverage your productivity by using CakePHP features on the server side to build your application server and use CakeAMFPHP to send data back and forth Flash/CakePHP. You can also have a HTML version of your Flash app without headeaches.
• laziza - Allows JSFL commands from remote host.
• wsdl2as WSDL stub compiler for ActionScript 3
• Granite Data Services - Free (LGPL) alternative to Adobe LiveCycle Data Services for J2EE servers.
• RED5 defense and statistic - Open source RED5 defense and statistic systems.
• AmFast - AmFast is a Flash remoting framework for Python that supports NetConnection and RemoteObject RPC and real-time Producer/Consumer messaging.
• whisperCast - Free (BSD) / Open source media streaming server. Flash media HTTP/RTMP streaming / publishing - extensible and high performance. (C++ / GNU/Linux)

• Alcon - An external output console for Actionscript debugging
• LuminicBox.Log - A logging API and output console for ActionScript
• As2logger - Logging Framework based on the Java Logging-API
• ZLog - *Very* easy log with MTASC and Flash IDE.
• EventController/LEC - A leak free event experience for AS3 enabling you to log out all your running events on your application through your favorite debugger or directly through the trace.
• Tornado - A runtime configurable logging solution with multiple publishers available.
• XFLAS2 - A MTASC & Flash IDE compatible logging solution, configurable at runtime or through xml configs, with automatic reflection.