Scratch

Scratch is a programming language that makes it easy to create your own interactive stories, animations, games, music, and art -- and share your creations on the web.

Free Open Source Mac OS X Windows Linux

FlashDevelop

FlashDevelop is a free and open source (MIT license) code editor for Actionscript (2 and 3), Flex (MXML) and HaXe.

Free Open Source Windows

KoolMoves

KoolMoves is a web animation authoring tool that creates Flash animations with multimedia slide shows, media players, and action scripting and frames for animated gifs....

Commercial Windows

Alligator Flash Designer

Create flash animations and websites, interactive presentations, forms, slide shows, photo albums, banners and Flash intros.

Commercial

Aphalina Animator

Visual tool for creating interactive SVG animations: HTML5 banners, svg icons, interactive web infographics etc.

Commercial Windows