CoAutor
From topic to a book ready to sell on Amazon
You decide the angle and the voice. The AI researches the market, writes the manuscript, designs the cover, and builds the files KDP requires, step by step.
The account is free. You only pay when you use the AI on a book, from R$ 39.
Covers built by CoAutor, with the same art generator and title compositor your book gets. These are examples, not books for sale.
Writing is the easy part. Publishing it right is what trips people up.
Alone, or with generic AI
- Market research done by guesswork
- Text that sounds like AI, full of repeated phrasing
- Cover sized wrong for what KDP requires
- PDF and DOCX adjusted by hand, file by file
With CoAutor
- Search Research shows what readers look for before you write
- Automatic review strips out overstatement and repeated phrasing
- Cover and spine sized exactly to your book
- PDF, DOCX, cover, and A+ Content exported ready to go
You direct the book and review every section. CoAutor handles the tedious part: research, formatting, and the files Amazon requires.
How it works
Research the market before you write
Search Research shows what readers look for on Amazon. Then you list the competitors, and the AI points to the space none of them took.
Write with AI guiding every section
You set the angle, title, and persona. The AI writes section by section, in the voice you chose, and reviews before moving on.
Publish with the files ready to go
PDF and DOCX formatted for KDP, a cover sized exactly right, A+ Content and a trailer, all exported from the same place.
26 kinds of book, from novels to word search
Each kind has its own path: in text books the AI writes with you; in puzzle and drawing books the program builds the pages, the answer key and the file.
Book to read
Text in chapters, written section by section.
Short reads
Short pieces, one per day or per theme.
For the reader to fill in
Pages with room for the reader to write.
Word games
The program builds the letter games and the answer key.
Every tool you would otherwise hire separately, already built in
Competitors and angle
You list the books already on the shelf, and the AI points to the space none of them took.
Search Research
What readers type into Amazon search, without paying a data provider for it.
A+ Content
14 banner templates for your book page, with text that reads clearly on mobile.
Cover for KDP
Cover and spine sized exactly to Amazon's specs, no Photoshop needed.
Trailer
A short book trailer, ready for social media.
Formatting
PDF and DOCX ready to upload to KDP, with the right bleed and margins.
Fact check
Every section gets a report of its claims, and you can look up a source online, with the page address.
Writing with the tab closed
Ask for the whole book and close your computer. An email tells you when it is done.
Chrome extension
Open a competing book on Amazon and send it to CoAutor for analysis: description, reviews and what readers complain about.
Import a manuscript
Already wrote the book? Upload the file and use the review, formatting and cover.
What a book costs when you hire each service
Example: a 30,000-word book, about 150 pages. Price ranges charged in Brazil, in Brazilian reais.
| Service | Hiring it |
|---|---|
| Ghostwritingper book | R$ 8.000 to R$ 50.000 |
| ProofreadingR$ 4 to R$ 20 per standard page, 120 pages | R$ 480 to R$ 2.400 |
| Interior layoutR$ 6 to R$ 12 per page, 150 pages | R$ 900 to R$ 1.800 |
| Cover by a designerR$ 500 on average | R$ 150 to R$ 5.000 |
| Without the writing: proofreading, layout and cover | R$ 1.530 to R$ 9.200 |
| With CoAutor: research, writing, review, formatting and cover | R$ 379 |
Ranges published by GetNinjas (layout), FreelaSemCrise (ghostwriting) and guides by proofreaders and cover designers, checked in October 2026. They are market references, not quotes: the real price depends on the professional and the book. In CoAutor the writing is done by AI and reviewed by you, not by a ghostwriter.
Already published a book and want to sell more?
Paste the title, description, 7 keywords and categories. CoAutor flags what KDP rejects and what could be better, in the order worth working on. Free, no sign-up.
Diagnose my book listingYou pay per book, not per month
Creating the account is free. Each book is unlocked with a one-time payment, by size. No monthly fee, and the package does not expire.
Activity book
R$ 39
one-time payment, per book
One puzzle, coloring, notebook or activity book
- Sudoku, word search, logic, coloring or notebook
- Pages built and checked by the app
- Cover with art, back cover and spine
- PDF ready for KDP
Short
R$ 199
one-time payment, per book
One text book of up to 15,000 words
- Competitor research, title and outline
- Writing with review and fact check
- Cover with art, back cover and spine
- PDF, DOCX, A+ Content and trailer
Standard
R$ 379
one-time payment, per book
One text book of up to 30,000 words
- Competitor research, title and outline
- Writing with review and fact check
- Cover with art, back cover and spine
- PDF, DOCX, A+ Content and trailer
Long
R$ 599
one-time payment, per book
One text book of up to 50,000 words
- Competitor research, title and outline
- Writing with review and fact check
- Cover with art, back cover and spine
- PDF, DOCX, A+ Content and trailer
No monthly fee
One payment per book. The package does not expire.
Pix or card
Through Stripe. CoAutor never sees your card number.
7 days to change your mind
Full refund if the AI has not been used on the book yet. If it has, we review it according to use.
Frequently asked questions
How much does it cost?+
You pay once per book, by size: R$ 39 (activity books), R$ 199 (up to 15,000 words), R$ 379 (up to 30,000) or R$ 599 (up to 50,000). There is no monthly fee, and the package does not expire.
What can I do without paying?+
Create the account, create the book, write and edit by hand, import a manuscript you already have, and export. Payment unlocks the AI on that book: research, writing, review, fact check, cover and marketing.
How do I pay?+
By Pix or card, on the Stripe payment page. CoAutor never receives or stores your card number.
What if I change my mind?+
You have 7 days to ask for your money back. If the AI has not been used on that book yet, we refund it in full. If it has, we review it case by case, according to how much was used. Just write to suporte@coautor.com.br.
Does the package have a usage limit?+
It has an AI generation limit, sized to write the whole book of that length with room to redo parts. If the limit runs out, generation stops on that book, and everything written stays yours.
Does the text sound like it was written by AI?+
The automatic review strips out repeated phrasing, overstatement, and the "not X, but Y" formula, the most common tell of AI text. You set the tone and persona before writing, and review each section before moving on.
Do I need to know Portuguese to use it?+
No. CoAutor now works in English too, from the first step to the final file.
What kinds of books does it work for?+
Nonfiction (business, health and wellness, personal finance, self-help), fiction (romance, mystery), puzzle books (sudoku, word search, logic puzzles, coloring books), and gift and activity books (trivia, joke books, guided journals, notebooks, how-to-draw books, and cut-out vision boards). The guided flow asks for an angle and a specific audience, so the more concrete your topic, the better the result.
How long does it take to finish a book?+
Writing runs on the server: you ask for the whole book, close the tab, and an email tells you when it is done. A 30,000-word book takes a few hours. The rest depends on how much you review. The flow has 13 steps, and you can go back and adjust any part before exporting.
Do the files match what Amazon KDP requires?+
Yes. PDF and DOCX with the formatting KDP asks for, a cover sized exactly to your interior and spine, and A+ Content banners in the size and file weight Amazon accepts.
Can the exported cover be used at a print shop outside KDP?+
Images are exported in RGB, the standard KDP and the screen use. A print shop that requires CMYK is not supported yet.
Where does my book get saved?+
In your account, accessible only to you and CoAutor. No other author can see your book.
Your first chapter starts now
Create your account, pick your topic, and let CoAutor handle the research, the writing, and the files for Amazon.