A simple Java CLI application to merge two Minecraft worlds into one, by combining region files and overwriting/skipping overlapping chunks.
Download the latest release and run the file using:
java -jar world-merger.jar /path/to/world/a/ /path/to/world/b/
Note that the world path should be the world root directory (containing level.dat).
Optionally, you can specify how overlapping chunks are to be handled using the -r option. Run
java -jar world-merger.jar -h for more information.