De MonsterDebugger

De MonsterDebugger is an open source debugger for Adobe Flash, Flex and AIR. De MonsterDebugger is made in Flex and AIR by design studio De Monsters.
Main features:
-Tree structure, lets you walk through your entire application on code-level
-Method testing, is very easy as you can run most methods and catch the results instantly
-Live editing, means you can edit properties and instantly see the effects in your application
-How it works, install De MonsterDebugger, import AS3 class, add any traces, start debugging
-Detailed traces, lets you trace Strings, Numbers, XML, Arrays, Objects with great detail
pen source, is the way De Monsters are releasing this application, you can use it for free