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Twelve subject lines, scored, with the reasoning shown.
Paste your email and audience, get twelve subject-line candidates grouped by strategy — curiosity, clarity, urgency, social proof — each scored for predicted open-rate lift and flagged for spam-filter risk.
It explains why each candidate works, so over time you need it less. The 24 Hour Pass exists for launch days when you're sending six campaigns before noon.
Subject Line Lab shows its cost before every run and covers you with a hard cap — or run free under an active time pass.