CoAuthor 1.2

Your book partner. Not your ghostwriter.

CoAuthor lives next to your manuscript. It helps with research, story bible, plot holes, and stuck scenes — then waits for you to accept or reject every change. You write the book. It does the parts that slow you down.

Start free See pricing

Free to write forever. CoAuthor is optional.

Chapter 12

The Harbor

Mira stood under the platform light. The train was late again. She almost texted Jonah — then put the phone away.

The platform smelled like wet iron. She counted the tiles between her boots and the yellow line — something to do with her hands that wasn’t the phone.

She left without looking back.

She almost turned. Rain hit the tracks. She walked.

…

The problem

ChatGPT doesn’t know your book.

You already do this: paste a chapter into another tab, hope it remembers her eye color, rewrite the robotic lines, then dig through six browser tabs for one fact. That’s not writing. That’s admin.

Side chats forget chapter three.
Generic AI prose sounds like generic AI prose.
Your bible lives somewhere else — or nowhere.
Readers can smell a book the author didn’t write.

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”

What CoAuthor is

Help that stays in the manuscript.

Open CoAuthor when you’re stuck. Close it when you’re flying. It can see your chapters, bible, and series — so you stop pasting your novel into a chat window.

Lives next to the chapter — not in another tab
Sees binder, bible, and series context
Suggests. Never overwrites without you

Chapter 12

The Harbor

Mira stood under the platform light. The train was late again. She almost texted Jonah — then put the phone away.

The platform smelled like wet iron. She counted the tiles between her boots and the yellow line — something to do with her hands that wasn’t the phone.

She left without looking back.

She almost turned. Rain hit the tracks. She walked.

…

For authors who hate AI books

You approve every change.

CoAuthor never overwrites your page. Every edit shows up as a suggestion. Accept it. Reject it. Move on. If you hate AI-written books, good — this product is built so the book stays yours.

Chapter 12

The Harbor

Mira stood under the platform light. The train was late again. She almost texted Jonah — then put the phone away.

The platform smelled like wet iron. She counted the tiles between her boots and the yellow line — something to do with her hands that wasn’t the phone.

She left without looking back.

She almost turned. Rain hit the tracks. She walked.

…

Jobs

What authors actually use it for

Not “generate a novel.” The boring jobs that steal draft days.

Research

Look up a detail, drop notes into the scene, or save them to the bible. Stop living in twelve tabs.

Chapter 12

The Harbor

Mira stood under the platform light. The train was late again. She almost texted Jonah — then put the phone away.

The platform smelled like wet iron. She counted the tiles between her boots and the yellow line — something to do with her hands that wasn’t the phone.

Somewhere down the line a horn sounded — long, then gone. She kept the letter in her coat and did not look at the clock again.

…

How you work with it

Three modes. Escalate only when you need to.

1
Ask
Think with you. Questions, continuity, research. Doesn’t touch the prose.
2
Partner
Suggests lines and fixes on the page. You accept or reject.
3
Agent
Bigger jobs: build bible entries, scan for inconsistencies, multi-step research.

Chapter 12

The Harbor

Mira stood under the platform light. The train was late again. She almost texted Jonah — then put the phone away.

The platform smelled like wet iron. She counted the tiles between her boots and the yellow line — something to do with her hands that wasn’t the phone.

She left without looking back.

She almost turned. Rain hit the tracks. She walked.

…

Creative control

It only shows up when you open it.

No background rewriting. No “AI improved your chapter while you slept.” When the dock is closed, it’s just you and the page — the way writing should feel.

Chapter 12

The Harbor

Mira stood under the platform light. The train was late again. She almost texted Jonah — then put the phone away.

The platform smelled like wet iron. She counted the tiles between her boots and the yellow line — something to do with her hands that wasn’t the phone.

Somewhere down the line a horn sounded — long, then gone. She kept the letter in her coat and did not look at the clock again.

…

Pricing

Pay for help only if you want it

Writing is free. CoAuthor is optional — like paying for ChatGPT, except it sits inside your book. Usage resets each day and week. No prepaid credits melting mid-scene.

Cancel anytime. Your drafts stay. The free desk still opens.

Full pricing →

Free

Try it on a real chapter.

$0

Limited use

Start free

Suggests edits — you accept or reject
Ask questions about your book
Basic continuity checks
Limited daily + weekly use

Popular

Pro

Daily writing partner.

$9/mo

Most authors start here

Get Pro

Everything in Free
More weekly room
Ask + Partner modes
Fast + balanced models
Continuity checks
Cancel anytime

Max

When Pro isn’t enough.

$19/mo

5× usage vs Pro

Get Max

Everything in Pro
5× weekly room
Full agent modes
Live research into the book
Stronger models
Cancel anytime

Free · Pro $9 · Max $19 · Max+ $49. Usage resets each day and week. Cancel anytime.

Writing tools (bible, map, Mac) are separate — see Typewriter plans.

Your book partner. Not your ghostwriter.

ChatGPT doesn’t know your book.

Help that stays in the manuscript.

You approve every change.

What authors actually use it for

Research

Three modes. Escalate only when you need to.

Ask

Partner

Agent

It only shows up when you open it.

Pay for help only if you want it

Free

Pro

Max

Write the book. Get help with the rest.