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
PASS, REVIEW or FAIL verdicts on emails
Detects unsolicited diagnoses and privacy intrusion
Catches generic flattery and fake familiarity
Identifies asymmetric asks and excessive homework
API integration for automated checking
MCP support for AI agents
Gmail and Outlook browser extensions
ChatGPT app integration
Structured JSON verdicts via API
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
Uses deterministic filters with fixed rules before applying AI analysis
Judges message form rather than facts it cannot verify
Scales across workflows and no-code platforms
Integrated with Zapier, Make, n8n, Clay and other tools
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
MailDignity
Chaptora