Roadcraft completesave editor by NakedDave.

to run with python: (make sure you have python 3.13.2 at least)

pip install -r requirements.txt
python completesaveeditor.py

or if you are happy with it just run the included .exe which does the same thing

Run the tool, pick your CompleteSave file, make changes, hit save. Editing simple things like money / xp / company name is a good place to start. I've not tested everything you can do; just because the generated save file is valid doesn't mean the game won't be upset (for example, if you add non-existent trucks or levels to your unlocks)

because the save file format is much much more complicated than the older games. trust me you don't want to do this manually

It's open source for a reason!