Sony just released an open source and engine agnostic level Editor.
It can be used to create levels/worlds for any engine and provide powerful API for this purpose.
the full source code is available here
to build the Editor you’ll need Microsoft VisualStudio 2010 or VisualStudio 2012/2013 (with some code hacks)
if for any reason you can’t build the editor here is a binary version for (64bits version)
File SHA1 checksum : 72b1dc0a01adb55dc46605f21b54f34e241e11b7