The debug console in Witcher 3 can be accessed via a mod at Nexusmods. There are a lot of commands available to add items, spawn monsters and to do other fun things. The information on this page is gathered from the comments on the mod-page and from my own research. Thought it would be convenient to gather the commands like this. You are welcome to contribute to this list.
Now that the debug console in Witcher 3 can be accessed, it is time to have some fun with it 🙂 To portal to certain locations in the game use these commands.