1 Login to the Kinetic Panel and Stop your server.
2 Go to the File Manager
3 Navigate to saves > worlds_local.
4 Then open the folder for the world you want, then download your _main[number].fwl2 file.
5 Go to the Unofficial World Generator and upload your world.fwl file.
6 Your world seed will then be shown at the bottom of the page.
