AI book writer
Write a full-length book with AI, chapter by chapter
Start from a one- or two-sentence pitch. FictionAI builds a story bible (premise, world, cast and chapter outline) that you edit, then writes each chapter from it in a workspace where you revise and export.
3 books free, no credit card. AI use is billed by OpenRouter to your own account.
Everything a book needs, in one place
A planning and writing workspace for long-form fiction, not a chat window.
Idea to story bible
Pick a genre, write a pitch and choose a length. One action builds premise, title, world, cast and outline.
Your choice of model
A Quality setting picks Fast, Balanced or Best. Settings → Advanced can use any model OpenRouter lists, including Claude, GPT and Gemini.
World and cast
Setting, time period, locations and world rules, plus characters with backstory, motivation and arc. Edit or regenerate any card.
Chapter workspace
Write a chapter, continue from the cursor, rewrite a selection or revise a chapter. Autosave, and drafts typed offline sync later.
Series
On Pro ($9.99/month), plan sequential, standalone or mixed series with a shared world and cast.
Export
Download DOCX, PDF, Markdown, plain text or HTML. DOCX opens in Word, Atticus and Vellum, and Amazon KDP accepts DOCX uploads.
FictionAI compared with a general chatbot
What a book-specific tool adds over writing in a chat window.
| FictionAI | General chatbot | |
|---|---|---|
| Story bible (world, cast, outline) | Yes | No |
| Chapters written from the outline and earlier chapters | Yes | No |
| Manuscript editor with autosave | Yes | No |
| Series with a shared world and cast | Yes | No |
| Export to DOCX and PDF | Yes | No |
| Choose the model per task | Yes | No |
A general chatbot can do much of this by hand; the difference is that FictionAI keeps the plan and the manuscript together.
Questions
Can AI really write a full book?
It can draft one, chapter by chapter, for you to edit. FictionAI plans the book first and writes each chapter from that plan and the chapters before it. Lengths run from a short story (~10k words) to an epic (~125k words). How long it takes depends on the model and how much you edit.
What AI models can I use for book writing?
The Quality setting uses Gemini 2.5 Flash Lite (Fast), the latest Claude Sonnet (Balanced) or the latest Claude Opus (Best). In Settings → Advanced you can pick any model OpenRouter lists for each task, including GPT and Gemini models.
How much does it cost to write a book with AI?
The Free plan costs nothing and Pro is $9.99/month. AI use is billed by OpenRouter to your own account with no FictionAI markup. FictionAI shows an estimate before each generation and the actual cost after, so you see what a book costs as you write it.
Can I publish AI-written books?
FictionAI exports DOCX, PDF, Markdown, plain text and HTML. It does not publish for you. Amazon KDP accepts DOCX uploads and asks you to disclose AI-generated content; check each store's current rules before publishing.
How is FictionAI different from ChatGPT for book writing?
ChatGPT is a general assistant. FictionAI is built around a book: a story bible you edit, a chapter outline, a manuscript editor that writes each chapter from them, series planning and export.