You own it, completely. Your book is plain text files in Documents › Proselon, on your own Mac, with no cloud manuscript storage and no lock-in. You can open those files in other apps, back them up, or walk away from Proselon entirely, and your book comes with you. If Proselon disappeared tomorrow, your manuscript would still be sitting in your Documents folder, readable in anything.

On our side, your manuscript stays on your Mac. Proselon doesn’t collect your book or store it in a cloud. When you talk to the co-writer, that text goes to whichever AI you chose, under your own account there, so how it’s handled is governed by your agreement with that provider, the same terms that already apply to any conversation you have with it. Please see their policy for specifics. Prefer to keep everything on your own machine? Run a local model through Ollama or LM Studio, and nothing leaves your Mac at all.

$6 a month, or $50 a year — everything included, no tiers, no credits, no per-word charge. It’s free for the first 30 days. The one thing Proselon doesn’t charge for is the AI: the co-writer works with your own Claude, ChatGPT, or Grok account — you sign in the way you always do — or a free local model on your own Mac, and we don’t sell it or mark it up. No API keys or metered usage from us.

Downloading Proselon and creating your account are free. When you start your trial in the app, you enter a card, and then you have the whole app free for 30 days — every feature, every engine, unlimited co-writing, not a stripped-down sample. After 30 days it becomes $6 a month (or $50 a year if you choose annual) — and we email you before that first charge, so it’s never a surprise.

Because we build for serious writers, and a card at the door keeps the trial for the people who mean to use it. The policies around it are simple and stated up front: we email you before we charge you, refunds come on request, and cancelling is one click.

Not for 30 days — and never without warning. Your first charge is at the end of the free trial, and we email you a reminder before it happens. We send a heads-up before the first renewals too. If you cancel before the trial ends, you’re not charged at all.

Cancel in one click, any time, from your billing portal — no email chase, no retention maze. And refunds are simple: anyone who asks gets one. If you were charged and changed your mind, email us and we’ll reverse it. Either way your manuscript is still plain files in your own Documents folder — cancelling Proselon never touches your book.

On a subscription engine, working with the co-writer counts against that plan’s usage limits, the same way chatting with the AI directly does. There’s just no second meter from us. Everyday drafting and editing conversations are the common case. Big jobs, like a whole-manuscript read of a very long book, use more, and if you’re pushing a huge serial hard, the larger plans give you more headroom. A free local model through Ollama or LM Studio has no usage limits at all: it runs as long as your own computer will.

Yes, though there’s no one-click Word import yet. Proselon books are plain text files, so the practical path is copying your chapters in: paste them into the editor, or drop text files straight into the book’s folder. Once they’re in, the co-writer treats them like any other part of the book.

Yes — a Proselon account, just an email and a password, created in the app the first time you open it (creating it is free). It takes a moment, and then you’re into your 30-day trial and writing. Your manuscript still lives in your own folder: the account is for the app, not custody of your book.

Your pick of six. Sign in the way you always do — no API keys necessary — with your Claude (Pro or Max), ChatGPT, or Grok (X Premium+ or SuperGrok) account. Prefer Gemini? Bring an API key from Google AI Studio, free to start and metered beyond the free tier. Or run a free local model on your own Mac through Ollama or LM Studio, with nothing leaving your computer. Whichever you choose, the app walks you through signing in.

Proselon is a Mac app for Apple Silicon (M-series) Macs. It opens like any Mac app and keeps itself up to date. Windows is coming soon, and there’s no mobile or web version today.

That’s the case it was built for. Your book lives in the app as your own files, and the co-writer reads what it needs when it needs it rather than trying to hold everything in its head at once. The continuity ledger carries across books in a series, so the wrong detail doesn’t slip in at chapter one hundred.