AI
AI built for authors.
Custom models. Fine-tuned for books, not chat. CoAuthor already sees your binder, bible, map, and research. It suggests a line. Nothing hits the page until you say yes.
One product
App
The desk in your browser. Binder, bible, map.
Devices
Keyboard, Go, or Typewriter.
AI
Custom models. Wired into the book. You keep the pen.
The paste loop
ChatGPT doesn't know your book.
You paste a chapter. It forgets her eye color. You rewrite the robotic lines. Research lives in twelve tabs. That's not writing. That's admin — and it makes you worse at the part only you can do.
The usual setup
ChatGPT
“Here’s chapter 12…” · forgot her eye color
Docs tab
paste · re-paste · lose formatting
Browser ×6
Victorian train schedules · half relevant
Notes app
“Jonah was at the pier?? check ch.4”
The job
Get smarter. Keep the process.
CoAuthor is not a novel generator. It is a partner that already lives in the manuscript: research, bible, map, the scene you are in. You leave smarter — a tighter line, a caught hole, a fact in the right card. The creative process stays yours. Close the dock and it is just you and the page.
Wired in
It already has the book.
Not a sidebar bolted onto a blank chat. CoAuthor reads the same desk you write in.
The page
It sees the chapter you are in. Suggests a line, a cut, a bridge. You tap yes or no.
Story bible
Cast, places, rules, threads — next to the chapter. Book three can match book one.
Map
Who owes whom. Who is dead. Who cannot walk into that room. On a graph, not a spreadsheet.
Research
Look up a detail. Pin it. Weave it into the scene or the bible. Stop living in Chrome.
Voice
Author DNA — a profile of how you actually write. Fine-tuned so help sounds like you, not a chatbot.
Series
Continuity across books. Eye color, timelines, who knows what. Flag what actually conflicts.
Languages
The manuscript's language is the craft language. Hindi, Arabic, Chinese — not English slop translated back.
Outline
Cards and structure next to the draft. Ask for a beat, a chapter spine, a missing scene. You keep the shape.
What it does
The work that steals the morning.
A date, a weapon, a street in 1891. Dig, pin, drop it in the scene or the bible. The tabs stay closed.
The models
Trained for this desk.
We pick the best models for prose, research, and continuity — then tune them for authors. Not a generic assistant with a writing prompt. A stack built to sit beside a manuscript, honor the bible, and wait for yes.
- — Best models for the job, swapped as they improve
- — Fine-tuned on how books work: voice, series, scene
- — Author DNA so suggestions match your sentences
- — No silent rewrite. You approve every change
Control
You approve every change.
No silent overwrite. No 'AI improved your chapter while you slept.' If you hate AI-written books, this is built for you. Open it when you're stuck. Close it when you're flying.
Price
Pay for help only if you want it.
The desk is free. CoAuthor has a free try, then credit from $5. You never need AI to write or export. The book is still yours if you never open the dock.
Free try, then buy credits. You accept every change.
FAQ
Straight answers
Does it write my novel?
No. It suggests. You keep the pen. If you want a generated book, other tools do that. CoAuthor is for authors who are writing the book themselves and want smarts without losing the process.
How is this different from ChatGPT?
ChatGPT lives in a thread and forgets the cast. CoAuthor sits in Typewriter — binder, bible, map, research. Custom models tuned for books. It never overwrites without you.
Do you fine-tune models?
Yes. We pick the best models for prose, research, and continuity, then tune them for authors — including Author DNA so help sounds like you. The stack is for this desk, not a chatbot with a writing prompt.
Will it remember my characters?
Yes, when they live in Typewriter: chapters, bible, map. That's why you stop pasting. Book three can still see book one.
What about research?
Ask from the page. Pin what matters. Weave it into the scene or a bible card. You don't leave the manuscript to go hunting.
Can it write in my language?
The book's language is the craft language. Live typing plus CoAuthor that honors it — not English first, translate later.
Is CoAuthor free?
There's a free try. Then prepaid credit from $5. The desk is free forever without AI.
Can I write without it?
Yes. Close the dock. It's just you and the page. Export works either way.
What is the best AI writing tool for authors in 2026?
If the novel must live somewhere durable: Typewriter with optional CoAuthor — manuscript-aware, propose-only, Author DNA. If you only want freeform generation: Sudowrite or a general chat model. Best stack is desk plus AI that knocks.
Typewriter vs Claude or ChatGPT for writing a book?
Claude and ChatGPT are chats. CoAuthor already has binder, bible, and map. Use general models for sparks. Keep the master file in Typewriter.
Write the book. Get help with the rest.
Start free. Try CoAuthor on a real page — your binder, your bible, your voice.
Start free