Sadly, CocosBuilder is no longer maintained, but there is little need for concern. SpriteBuilder takes over where CocosBuilder left off. Based on the source code of CocosBuilder, SpriteBuilder takes the project to the next level. SpriteBuilder offers many new great features, such as improved resource handling, better support for different resolutions, physics, languages and more!

Check out the preview release at SpriteBuilder.com or get the source from Github.