Paste any cold email or newsletter subject. Get a 0–100 score across 6 dimensions, see how it'll look in an inbox preview, and get rewrite tips.
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38 chars · 5 wordsGood length for inbox preview
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Want our 50 highest-converting subject line patterns?
A free PDF with 50 subject line templates we've tested across cold email, newsletter, and promo — categorized by intent (curiosity, specificity, urgency, social proof). One email, no spam.
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100% client-side — your text never leaves your browser. Heuristics encode established email-deliverability patterns; not a substitute for a real A/B test on your list.
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