Hastily hacked tool to migrate player inventories from one world to another. Based on the NBTExplorer by jaquadro. There is currently no installer available, just unzip and start NBTConverter.exe from cmd.
Windows XP or later, .NET Framework 2.0 or later.
Untested, but since NBTExplorer is compatible with Mono 2.6 or higher the converter should work as well.
NBTExplorer is compatible with recent Mono runtimes, at least 2.6 or later.
Minimally, your system needs the mono-core and mono-winforms packages, or whatever package set is equivalent.
There is no native Mac Version for the converter, but it should work with Mono.
The Windows version of NBTExplorer can still be used if the Mac version does not work. You will need to install the Mono runtime, and then run NBTExplorer with Mono from the command line.