bookmoth is a writing app that learns your voice and keeps your whole story in context to help you plan, draft, and edit, with as much or as little AI as you want.
Launch price of $49 until the solstice, 21 June. Then $99.
“Every AI writing tool I tried produced text that sounded like AI. Competent, clean, utterly lifeless. I built bookmoth because I wanted a writing app that learns how I actually write, stays in my voice, and only helps when I ask it to.”
Stu, founder
Both written by Claude Opus 4.6. The only difference is that the right one was governed by the writer's own voice profile.
Brief. Voice. Plan. Draft.
A guided conversation draws out your premise, characters, tone, and emotional arc. The richer this is, the better everything downstream becomes.
Paste in your own prose. bookmoth analyses your sentence rhythms, dialogue patterns, and vocabulary at the mechanical level, then compiles it into a writing profile that governs every draft. Not just English: it works across major European and Asian languages too.
Every chapter breaks down into scenes, each with its own goal, conflict, and turn. Generate a plan from your brief, paste in an outline you've already written, or import an existing manuscript. Change the plan and the manuscript follows. Change the manuscript and the plan stays in sync.
When you want a draft, each scene is written with full awareness of what came before and what comes next. Polish a single scene, run another pass on a chapter, or start a fresh version without losing anything. Choose your model: Anthropic, OpenRouter, or a local LLM.
The codex
Most tools make you build the codex by hand. bookmoth builds it for you.
As you draft and import, bookmoth scans your chapters, proposes new characters, places and lore, and flags contradictions before they become canon. Nothing is saved until you accept it, and you decide what the AI sees, per entry and even per detail.
Give a character a handful of example lines and bookmoth writes their dialogue in that voice, the same way it writes your book in yours. Aliases keep one person together however you name them, and relationships hold your world consistent.
The editor
A conversation inside your manuscript, always reading your live prose.
Highlight a sentence and say what you want, and the editor proposes a change to just that selection, shown as a diff you accept or dismiss. Ask for a structural read and it answers like a colleague who already knows your book. It can even reshape your chapter cards and scenes through the conversation.
Tighten a passage, raise the tension, or check continuity, all in plain language with the whole book in context.
Select a passage, describe the change, and it lands only there, shown as a reviewable diff.
Every change goes through a diff you review and saves as a version you can roll back.
Themes
Three colourways, each with a light and a dark, and a live picker that reskins the whole app as you flip between them. bookmoth, Paradice, and Mithril.
Paste a few paragraphs. Get a free voice portrait by email. No account needed, no strings. Just an honest editorial read of your prose. Works in most major languages.
Get your voice portrait
See it work
Ask the Editor reads your chapter in the context of your entire manuscript, your brief, and your voice profile. Structural, tonal, and craft-level notes.
Every chapter carries its own versions. Draft, revise, start fresh. Your earlier work is always there. Nothing is overwritten, nothing is lost.
No account. No cloud. No analytics. Your manuscript, your brief, your writing profile: all stored on your machine.
One fee. No subscription. Ever.
Launch price of $49 until the solstice, 21 June. Then $99.
Bring your own API key (Anthropic or OpenRouter). A chapter costs anywhere from 2 to 30 cents depending on your model. You control your spend.
You buy bookmoth once. Updates are free, forever. No tiers, no usage caps.
AI costs are between you and your API provider. A chapter costs anywhere from 2 to 30 cents depending on the model: Claude sits at the top end for maximum quality, OpenRouter models bring it down to a few cents, and local models are free. You see exactly what you spend in your own dashboard.
Most AI writing subscriptions charge $19-29/month. In three months you've spent more than bookmoth costs forever.
$49. Once. No subscription. Free updates forever.
