WARNING: The Save Editor is unofficial and not supported by the CoC2 development team. They are not responsible for any damage to your saves that it causes.
Saved games can be edited either with external software or manually. In both cases, you need to use "Save to file" to produce a save that can be edited.
Because the files are not nominally human-readable, all of the content is dumped in a single file. To make them easier to read, you can use Notepad++'s JSON Viewer plug-in. You can install it from Plugins > Plugins Admin.... After the plug-in is installed, when you open a save file you can select Plugins > JSON Viewer > Format JSON to make the code more readable.
When editing JSON files, make sure that all quotes and brackets are closed, and there are no missing commas.
Change the value for the "hash" variable to "" to remove the on-load message about hacked saves.