GhostAI: Your AI Writing Collaborator
GhostAI has a certain set of skills…
The GhostAI skills are open source (MIT) and under active development. Features, skills, and capabilities evolve based on real manuscript feedback from authors using it in the wild.
GhostAI is an AI writing collaborator purpose-built for book authors. Unlike AI tools that generate slop from a prompt, GhostAI interviews you, challenges your structure, and drafts in your voice. It understands your full manuscript — not just the chapter you're working on — and maintains context across every skill.
Use it two ways: built into the Leanpub plain text editor or visual editor, for authors who want a seamless in-browser experience, or as a free, open source set of skills for your favourite coding tool like Claude Code or Codex. Same skills, same intelligence, same voice — your choice of where to write.
To use GhostAI in the Leanpub plain text editor or visual editor, you can either subscribe to a Max or Ultra author plan, or simply buy GhostAI credits, which can be used with any author plan.
Buy GhostAI credits — or subscribe
Starter Pack
Enough to get going, create an outline for your entire book with Start, and outline a few chapters with Outline. If you're at the beginning of your writing journey, this will really help you!
$19.99one-time
200 credits · never expire
- 200 GhostAI credits
- Runs Opus 4.8 on every prompt
- Use across every GhostAI skill
Plus Pack
Triple the Starter Pack — room to keep going.
$49one-time
600 credits · never expire
- 600 GhostAI credits — 3× the Starter Pack
- Runs Opus 4.8 on every prompt
- Use across every GhostAI skill
Progress Pack
Make real progress — 7× the Starter Pack.
$99one-time
1,400 credits · never expire
- 1,400 GhostAI credits — 7× the Starter Pack
- Runs Opus 4.8 on every prompt
- Use across every GhostAI skill
Best value
Book Pack
Draft and edit a whole book — 25× the Starter Pack.
$349one-time
5,000 credits · never expire
- 5,000 GhostAI credits — 25× the Starter Pack
- Lowest price per credit
- Runs Opus 4.8 on every prompt
Prefer a subscription? Max Author includes GhostAI with a monthly usage allowance from $34.99/mo, and Ultra Author gives you 5× the allowance — plus everything else in a Leanpub Author Membership.
See Author MembershipsSkills
Getting Started
- Start — A conversational onboarding for your book. GhostAI interviews you about your topic, your audience, and what you're trying to accomplish, then builds a full chapter outline and sets up your manuscript so you can start writing immediately. No blank page.
- Outline — An in-depth chapter planning session. Goes beyond a flat table of contents: challenges your structure, asks what each chapter is really trying to do, and helps you decide what deserves a chapter versus what belongs as a section or a callout. Good for restructuring an outline you already have or building one from scratch.
- Organize — Triage for a pile of scattered notes and half-chapters. Reads everything you have, then proposes where each piece belongs: the paragraph stranded in the introduction that's really a chapter-six point, the story you told twice, the cluster of notes that's secretly a missing chapter. For the author who has plenty of material but can't see the shape of it yet.
Writing
- Draft — Blank page to first draft. Interviews you about what the chapter should do, proposes a section-by-section plan, gets your approval on each approach before writing any prose, then drafts it.
- Expand — Bullets to prose. Takes rough notes, outline points, or stream-of-consciousness jotting and grows them into finished paragraphs. Preserves your intent and phrasing where it works, smooths what doesn't.
- Interview — Talk your chapter into existence. The AI asks short, voice-input-friendly questions. You answer in your own words (typed or via voice input like Wispr Flow). The transcript becomes prose with your verbatim phrasing leading. The strongest voice match of the three doors, because the words are literally yours.
- Story — Pulls a real anecdote out of your head and onto the page. Interviews you one question at a time about a moment you actually lived through, shapes it into a tight anecdote in your own voice, and files it in the chapter where it earns its place. Turns 'I have a career full of stories' into book material instead of stories that never get written down.
- Examples — Turns your advice into the practical artifacts readers keep and recommend: the scripts, the 'say this, not that' tables, the checklists, the fill-in worksheets, the worked examples. It extracts and formats your expertise rather than inventing it — when an artifact needs the exact wording only you know, it asks you for it.
Editing
- Edit — The daily driver. A copy editor for one chapter at a time that runs specialist passes: grammar, clarity, tone and voice consistency, technical accuracy, advisory AI slop detection, and a pre-flight publish checklist. Every change is a suggestion you accept or reject — like a real editor in track changes.
- Rewrite — Section-level structural revision. For when a passage exists but the staging is wrong — unclear POV, buried lead, wrong order of ideas. Diagnoses the structural bug first, then proposes two structurally different rewrites so you pick the angle rather than nudge your way into it.
Review
- Review — The development editor. Reads your entire manuscript, not just a chapter. Catches the problems no individual edit pass could catch: a concept introduced in chapter 2 but defined in chapter 5, an argument that stalls in the middle, the same point repeated three times across different chapters, pacing that drags or rushes. This is where GhostAI's cross-chapter memory matters most.
- Reader — Test a passage on a stand-in for your target reader before a real one ever sees it. GhostAI becomes the reader and reacts honestly — where it gets confused, the question you left unanswered, the moment it starts skimming, the 'okay, but what do I actually say on Monday?' — then names the two or three changes that would land best. Catches the expert's blind spot of writing for peers instead of for the person who needs the help.
Progress
- Status — A dashboard for your book at a glance. Word counts per chapter, estimated reading time, chapter length balance (are any chapters three times longer than the rest?), how much is drafted versus still outline. Also estimates costs for running the other GhostAI skills against your current manuscript, so you can budget before kicking off a full review.
Stuck or Overwhelmed
- Coach — Encouragement for the moments the whole book feels like too much. Not a writing tool — a confidence tool. It reads your manuscript so it can point at real, specific progress instead of empty cheerleading, takes the doubt seriously instead of waving it away, and gives you one small next step rather than a daunting list. Most first books die because the author loses faith, not because the writing was bad; this is the skill that keeps you in the chair.
- Unstuck — A thirty-second intervention for one specific spot you can't get past. Offers a few concrete, genuinely different ways forward — a throwaway opening sentence to react to, a fresh angle, or permission to drop a note and move on — then hands the momentum back to you. The spark, not the engine.
Voice & Training
- Voice — Manage your voice profile across machines, projects, and co-authors. Update it from a fresh writing sample, promote it from your laptop into the book's git repo so co-authors share the same voice, or copy it across machines.
- Train — Teach GhostAI what you think about your own writing. Three short interviews: what you're good at, where you struggle, and the patterns you can't stand seeing on your page. Answers are synthesized into your style guide so every other skill applies them automatically.
GhostAI in the Leanpub Editor
GhostAI is built directly into the Leanpub editor — both the plain text editor and the visual editor. Open the GhostAI panel while editing any chapter, pick a skill, and start writing — no setup, no API key, no installation. The same skills, the same voice profiling, the same manuscript-aware intelligence, running right alongside your text.
The on-platform experience is designed for authors who want the power of GhostAI without leaving their writing environment. Changes are applied directly to your manuscript with automatic before-and-after snapshots, so you can always roll back. Every suggested edit is a proposal you accept or reject — nothing is auto-applied unless you turn that on.
GhostAI as Open Source
GhostAI is also a free, open source set of skills (MIT license) that you install into your favourite coding tool — Claude Code, Codex, or any agent that supports skill plugins. Clone the repo, run the install script, and every skill works on any Markua manuscript — whether it's a Leanpub book or not. You bring your own API key and pay only for what you use.
The open source version is ideal for authors who want full control over their AI costs, prefer their own editing environment, or write manuscripts outside the Leanpub web editor. It's built on a similar codebase to the on-platform experience — improvements to one tend to benefit the other.
Requirements
On-Platform (Leanpub Editor)
- A Max or Ultra author plan membership on Leanpub
- A web browser — that's it
Open Source (Your Own Tool)
- A coding tool that supports skills — Claude Code, Codex, or similar
- An API key for your chosen tool's AI provider
- macOS or Linux (WSL2 on Windows works fine)
- A manuscript in Markua format (or run Start to create one)
How to Get GhostAI
The GhostAI skills are free and open source under the MIT license. Clone them from github.com/leanpub/ghostai and run the install script — see the repo's README. GhostAI inside the Leanpub editor is included with the Max author plan or Ultra author plan — no setup required. If you want hands-on training from the people who built it, attend our GhostAI Workshop, Full Day Workshop, or Book Bootcamp.
The Future of GhostAI
The GhostAI skills are MIT-licensed and evolve continuously. Improvements to the open source skills flow into the on-platform experience and vice versa. The workshops and Book Bootcamp teach you to use GhostAI effectively on your own manuscript, with hands-on help from the team that built it. New skills, better prompts, and refinements ship as authors use GhostAI in the wild and tell us what works.
Frequently asked questions
- Why isn't there a free trial?
- Because GhostAI runs Opus 4.8 on every prompt. We don't quietly swap in a cheaper model to pad a free tier — you get the best model every time. Try it for $19.99 with a Starter Pack that never expires, or get it bundled with a Max or Ultra Author subscription from $34.99/mo.
- Do credits expire?
- Credit-pack credits never expire — they're yours. A Max or Ultra Author subscription also includes a monthly allowance that resets each month (use it or lose it), on top of any pack credits you've bought.
- What does a session actually cost?
- It depends on how much manuscript context a skill reads and writes. Multi-turn skills cache your system prompt and voice profile, so longer sessions get cheaper per turn rather than more expensive.
- Do you discount the tokens?
- No. We don't mark down your usage by downgrading the model. The price reflects real Opus 4.8 usage — which is exactly why the output is worth keeping.
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