Know which headline wins before you spend traffic on it.
Stage
Startup
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Founded
2025
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Based in
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Pricing model
Freemium
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Pricing
Free: 10 credits (one-time). Monthly: $7/mo for 70 credits. Yearly: $65/yr for 600 credits.
Free: $0/month with 5 rankings and 60 Claude-written options monthly. Creator: $19/month with 100 rankings and 2,500 options. Pro: $49/month with 600 rankings and 6,000 options. Agency: $149/month with 3,000 rankings and 20,000 options.
Key features
TYPE-FORMULA pipeline that extracts insight types (diagnostic, wisdom, contrarian, data-backed, framework, story) and applies viral structures
Knowledge Bank to store, browse, and reuse extracted insights
10+ viral formula structures including parallel repetition, conditional framework, and bridge analogy
Chrome extension for scheduling posts directly to Substack
Rich-text editor with HTML and plain text export
MCP integration for Claude and Cursor
Automatic article URL processing from published or draft posts
Priority processing for paid plan users
Head-to-head comparison of up to 200 variants
Bradley-Terry model ranking with calibrated odds
Honest uncertainty verdicts: Clear, Lean, Too close to call
Brand profiles to calibrate accuracy on your audience
Works for YouTube titles, subject lines, ad headlines, and article headlines
Accuracy measured on 9,841 held-out A/B tests
What makes it different
Designed specifically for Substack writers with formulas trained on viral patterns
Two-stage TYPE-FORMULA process instead of generic AI summarization
Knowledge Bank compounds over time as more articles are processed
From URL to scheduled post in minutes with no copy-paste needed
Credits never expire at your own publishing pace
82% accuracy on clear calls, trained on thousands of real A/B tests never seen during tuning
Honest about uncertainty instead of always crowning a winner
56 times cheaper than Claude Sonnet while maintaining comparable accuracy
Custom calibration to your audience's behavior via brand profiles
Compare versions in both orders to cancel out model bias