Deletes chunks in region files with InhabitedTime less than the input value.
https://github.com/Sladki/MC-UnusedChunksDeleter/raw/master/jar/UnusedChunksDeleter.jar
How to use: put in the server or save directory and launch
java -jar UnusedChunksDeleter.jar time threads
Where 'time' is time in ticks, chunks with InhabitedTime lesser than will be deleted, and 'threads' is number of threads (optional). Clean region files will be at 'world/region/clean' directory, source region files will not be changed. Copy files in 'world/region' directory to another folder (your backup) and replace with "clean" region files.
This program uses Minecraft AnvilConverter files. https://assets.minecraft.net/12w07a/Minecraft.AnvilConverter.zip