Free: $0 forever with daily allowance after 7-day trial. Pro month: $1.99 for 30 days. Pro year: $19.99 for 365 days.
Octavo: Free forever (1 project, 3 research files, limited AI usage). Quarto: $20/month or $200/year (unlimited projects, 50 files per project, 10× more AI usage). Folio: $100/month or $1,000/year (unlimited research files, 5× more AI usage than Quarto, priority queue, early access to new models).
Key features
Fix with grammar and tense correction
Native rewrite suggestions
Works in every application with text boxes
Suggested replies with four options
Translation between languages
Custom snippets with shortcuts
Personal writing style customization
Explanation of corrections
Optional chat context for tone matching
Context-aware AI suggestions that read your chapters first
Source-grounded edits from PDFs, URLs, and YouTube transcripts
Red and green diffs requiring your approval
Export to Amazon KDP, Apple Books, Lulu, IngramSpark, Google Play Books, Draft2Digital
Chapter-aware AI agent
Citation engine with Chicago-formatted bibliography
Front matter and back matter editor
Version history to save and restore manuscript versions
Clean PDF and EPUB export with professional typography
What makes it different
No subscription, pay once with no auto-renewal
Works across all Mac applications through accessibility
Preserves personal writing voice with customization
Keeps your entire book and research in context, unlike chat windows that start fresh each session
Returns edits as approvable diffs you control, not auto-inserted changes
Built specifically for book publishing with real front matter, back matter, and professional export formats
nonolingo
Chaptora