This was recommended by Jason Alexander, but the gist of this is that Raptor Write is basically a sort of freeware creative writing software where you bring in AI via API keys (so it can even be a sort of "pay as you go" model too if you use models like Claude or ChatGPT) and prompt writing. It's the closest thing to a free version to NovelAI (NovelCrafter from what I've seen of the videos is its own beast altogether) and it's worth checking out. Below is the video from Jason.