Write your novel with AI. Keep every word on your own computer.
Copperas is a writing app for long-form fiction with a full editorial AI built in — drafting, multi-depth reads, beta readers, an agent assessment. Unlike the cloud tools, your book stays a plain file on your own machine. Unlike the local ones, you actually get the AI.
Only one has it all.
Scroll the table sideways to see every tool →
| Copperas | Scrivener | Sudowrite | Novelcrafter | |
|---|---|---|---|---|
| Local-first — on your own disk | Yes | Yes | Cloud | Cloud |
| Works offline | Yes | Yes | No | No |
| AI drafting | Yes | None | Yes | Yes |
| AI editorial reading | Three depths | None | Rewrite + Describe | Via chat |
| Local version timeline | Yes | Manual snapshots | Cloud only | Cloud only |
| Character & world memory | Automatic | Manual binder | Manual (Story Bible) | Codex |
| Voice input & read-back | Yes | None | None | None |
| AI included — no API key | Included | No AI | Included | Bring your key |
| Interface in EN / ES / FR | Yes | Preview (in-app) | EN only | EN only |
| Free to write. Pay only for AI. | Yes | No — pay to write | No — pay to write | No — pay to write |
| Price | Free + $18–42/moAI is the only paid tier | $59.99 onceNo AI | $19–59/mofrom $10/mo annual | $4–20/mo+ your API costs |
Comparison as of July 2026. Scrivener, Sudowrite, and Novelcrafter are trademarks of their respective owners; we respect what each does well.
The field splits into two camps. Copperas is the bridge.
Until now, writers have had to pick a side. The tools that keep your book on your own machine won't touch AI. The tools with real AI keep your book in their cloud. That gap is the whole reason Copperas exists.
Own your files — but no AI.
Beloved, private, offline. Your manuscript is yours. But the makers have said no to AI, with no plans to add it — so as AI becomes part of how books get written, this camp has chosen to sit it out.
Real AI — but in the cloud.
Powerful generative and editorial tools. But to use them, your book — and its version history — lives on someone else's servers, and the interface is English-only. You trade control over where your work lives for that capability.
Copperas is the only one that's both.
Local-first like the tools you trust, with a full editorial AI like the ones you envy — and your manuscript never leaves your computer to get it. That's the column checked all the way down.
Free to download. Free to write.
The complete environment — editor, chapter navigation, version timeline, import, export — works without an account and costs nothing. AI features are the only paid tier. Try the environment first; add AI when you're ready.
Works fully offline. Your manuscript is always on your machine, always readable in any text editor.
Automatic snapshots before every AI apply. See exactly how your prose changed, not just that it changed.
Compare any two versions of your manuscript inline. Restored changes are surgical — one line at a time if you want.
Bring in an existing manuscript from Word. Export a clean, submission-ready document at any time.
Handcrafted themes for the light, warmth, and mood that fit the way you work and the way you think.
Hides every panel. Centers the chapter. The interface disappears and leaves only the page.
For writers who choose not to use AI assistance: Copperas is for you as well, and it is free of charge. We respect your choice and your conviction, and we hope you find it a useful tool for writing your next novel.
Purpose-built for every stage of the writing process.
Every role here runs on the Longform Prose Engine — purpose-built infrastructure, not a chat window bolted onto a generic editor. It keeps a persistent understanding of your project — characters, plot threads, chapter structure, style rules, continuity — and brings it to each interaction, choosing the right model, the right context, and the right editorial lens, deepening with every session you write.
Understands your project.
Characters, plot threads, chapter structure, your style contract. New projects start from one of 25 pre-built genre templates. Talk to it in plain language and the right specialist picks up the work.
Three depths of attention.
Quick Read catches structure and continuity. Close Read marks prose patterns and missed opportunities. Deep Read gives full literary attention to every line.
Drafts, revises, expands.
Write a scene from scratch. Expand a passage. Tighten a chapter. Every instruction runs through your style contract and reference files. Nothing touches the manuscript until you click Apply.
Three readers. No comparison.
Three independent AI readers, each with a different lens, responding without seeing each other's reactions — the same variation three real humans would give you.
The truth about your manuscript.
A senior literary agent reads your book and gives an honest professional evaluation. It reads the way an agent would — commercially, structurally, honestly.
The shape of your story.
Maps your novel's momentum from opening to final page. Per-chapter pacing grades, an intensity score, and the most important momentum issues, ordered by impact.
Nine categories. No judgment.
Cites specific passages with explanations and suggested alternatives across nine categories. Run only the ones relevant to your manuscript.
Compounds across sessions.
Facts from every session are harvested and fed back into future sessions automatically. The more you write with Copperas, the more precise every interaction becomes.
When you're writing, the interface disappears.
One keystroke hides every panel and turns on Typewriter mode — a steady block cursor holds the center of the screen while the page scrolls up to meet each word. Try it.
Full view gives you the chapter navigator and the editorial AI. Focus collapses both and switches on Typewriter mode — the block cursor stays mid-screen and the page rises to meet it, so your eyes never leave the center of the page. Typewriter is also its own toggle (⌘⇧T) if you want it without hiding the panels.
Writing a novel takes time. The tool you write in becomes the place where you spend that time — the room you think in. It should feel good to be there.
Copperas is designed to disappear. The interface is quiet. The typography is clean. Six handcrafted themes let you choose the light, warmth, and mood that suit the way you work. The editor shows your chapter with the surrounding scenes visible for context, and everything else stays out of the way until you need it.
There are no toolbars crowded with icons. No sidebars competing for your attention. No notifications. When you are writing, you see your prose and nothing else. When you need help, the AI Assistant is one keystroke away. When you are done, it closes and the words are all that remain.
This is intentional. Flow requires trust — trust that the tool will not interrupt you, that it will not lose your work, that it will be there when you come back tomorrow. Copperas earns that trust by being simple, fast, and honest about what it is doing.
The best writing sessions are the ones where time disappears. You sit down, you find the thread, and the next thing you know two hours have passed and the chapter is alive.
Copperas is built to protect those sessions. Voice input lets you talk through a scene without breaking eye contact with the page. The AI responds in conversation, not in forms and buttons. Timeline snapshots happen silently in the background so you never have to stop and save. When the editor finds something in your prose, it tells you in plain language and waits for your decision — it does not auto-correct or rewrite without asking.
Every design choice serves the same question: does this help the writer stay in the work?
Free to write. Pay only for AI.
The writing environment is free forever. AI features run on credits that map directly to actual AI cost — you always know what you're spending and why. No opaque limits, no surprise overages.
- Full writing environment
- Chapter navigator & editor
- Automatic version timeline
- DOCX import and export
- Six handcrafted themes
- Focus mode
- Everything in Local
- AI Assistant
- Quick Read + Close Read
- Drafting Assistant
- Beta Readers
- Agent Assessment
- Session memory
- Everything in Basic
- Deep Read
- 37% lower cost per credit
- Everything in Extended
- Maximum editorial depth
- 47% lower cost per credit
All prices in USD. Credits carry over when you top off ($5 for 2,000 credits, repeatable). Free trial includes 1,500 credits.
Own your book. And have the AI too.
Download the free writing environment and keep your manuscript on your own computer. Add the editorial AI whenever you're ready — a 1,500-credit trial to start, then Basic $18, Extended $30, or Best Seller $42 a month.
Download free macOS and WindowsApp interface available in English, Spanish, and French · German and Dutch coming soon