If you're looking for a StoryNest.ai alternative, NovelAI is another good option. It's a subscription-based service with AI for authorship and storytelling that lets you write literature without censorship or restrictions. With tools like character visualization, a text adventure module, customizable editors, and a lorebook for world-building, NovelAI can accommodate a wide range of writing styles. Its pricing options include a free trial, Tablet ($10/month), Scroll ($15/month), and Opus ($25/month) tiers for different levels of use.
Another good option is Subtxt, which can help writers construct narrative structure and consistency with AI assistance. Subtxt includes tools like Narrative Agents, Subtxt Muse, and Storyforms to construct rich narratives and explore professionally-curated analysis. It's designed for screenwriters, novelists and playwrights, and offers three pricing tiers: Subtxt ($25/month), Subtxt Pro ($45/month), and Subtxt Infinite ($250/month).
For a more specialized focus on fiction writing, Sudowrite is an AI writing assistant designed to help you get past writer's block and write more efficiently. With tools like Describe, Story Bible, Write, and Edit, Sudowrite is good for different stages of writing. It offers a free trial and three tiers of pricing: Hobby & Student, Professional, and Max, so it should be adaptable to your needs.
Last, ProWritingAid is a general-purpose writing assistant with AI tools to help you improve style, structure and impact. It offers detailed story critiques, real-time checks, readability tests and more, and it works with Microsoft Word, Google Docs, Scrivener and major web browsers. ProWritingAid has four tiers of pricing, including a free option for basic suggestions, so it's useful to a broad range of people.