If you're looking for something besides AuthorGPT, Novelcrafter is a full-featured writing environment with a personal Wiki for tracking story details and a range of AI tools to help with outlining, writing and editing. It's good for both planners and pantsers, with customizable tags and labels, and lets you control AI prompt settings.
Another good option is NovelAI, a subscription-based service that uses AI for authorship and storytelling. It's got tools like character visualization, a text adventure module and a customizable editor. NovelAI also comes with encrypted storage for its AI modules for writing in different styles and tools for tracking world-building details.
If you want something more interactive, StoryNest.ai has tools for crafting compelling stories, novels and interactive stories. That includes character creation and world-building tools, AI-boosted editing and voice narration. The service accommodates a variety of formats and lets you collaborate with others, so it's good for a broad range of writers.
Last, Sudowrite is geared for fiction authors to try to break through writer's block with its AI writing assistant. It's got tools for idea generation, outlining and editing, and includes tools like Describe, Story Bible and Rewrite. Sudowrite is designed to help you be more creative, productive and fun while writing.