Bring the writing room to your Mac.

Installing on macOS

1. Download it. Click the button for your Mac.
2. Drag it to Applications. Open the disk image, drag the Proselon icon across.
3. Open it and sign in. It opens with a double-click, being signed and notarized by Apple. Sign in with the account you made on the web. Should you have come to the app first, it sends you to the website for an email and a password, and your 30 free days start the moment that account exists.
4. Sign into your AI. Whichever you use, signed in the way you always do. The app walks you through it, then opens your first book.

Installing on Windows

Proselon is signed, so Windows itself no longer stops you at the door. Your browser may still hesitate. Browsers keep their own count of how often a file has been downloaded, and a new release has not yet been downloaded often, which is a matter of the file’s age rather than anything about the app. One click gets you past it.

Windows 10/11 (64-bit)

1. Download the installer. The button above gets you Proselon-Setup.exe.
2. Tell your browser to keep it. Chrome and Edge both pause a file they have not seen many times before, saying something to the effect that it is not commonly downloaded. In Chrome the download sits unfinished, named .crdownload, until you approve it: open your downloads (the ↓ beside the address bar) and choose Keep. In Edge, Show more → Keep anyway.
3. Follow the installer, then sign in. The app asks for the account you made on the web. Should you have come to the app first, it sends you to the website for an email and a password, and your 30 free days start the moment that account exists.
4. Sign into your AI. Whichever you use, signed in the way you always do. The app walks you through it, then opens your first book.
5. That was the only time. Updates install themselves in the background from here, with nothing to approve.

Proselon is free for 30 days and takes no credit card to start. Before the trial ends we email you. Add a card then and it is $6 a month (or $50 a year), or do nothing and the trial lapses with nothing charged. Cancel in one click at any time, and ask within 30 days of a charge to have it back. The co-writer itself works with your Claude, ChatGPT, Grok or Gemini account, signed in as you always sign in, or a free local model through Ollama or LM Studio. No API keys necessary, and no metered usage from us. Your books are plain files in Documents › Proselon, and your manuscript stays on your own computer. The app signs into your account and checks for updates, but your book is never uploaded to us.