Decrypting the save. - HecknTarnation/Minecraft-Dungeons-Savefile GitHub Wiki

In order to edit the save file, you must decrypt it first. To do this, we are going to use dungeon tools.

  1. First, find your save file, it will be under your Saved Games file. C:\Users\NAME\Saved Games\Mojang Studios\Dungeons\NUMBERS\Character.
  2. Back up the file by making a copy of it (you should do this every time).
  3. Now drag the file onto the dtools.exe, this will create a JSON file that you can now edit.

When you are done editing the file, drag the JSON file onto dtools.exe and move the created .dat file back into your saves.

Note: If the file fails to load (you will be prompted to create a new character if that was you only save) make sure you properly followed the tutorial and didn't make any typos. Make sure to also check that any equipment you edited also loaded correctly.