// SUBJECT LINE A/B PREDICTOR

Pick the winner
before you hit send.

Paste 2-5 cold-email subject lines. We score each across 6 dimensions — length, personalization, specificity, curiosity, spam-risk, and freshness — predict the winner with a concrete why, and rewrite the weakest line for you.

Candidate subject lines2-5 · keep tokens like {{first_name}} as-is

Audience

Send goal

// Add 2+ subject lines above to predict the winner

Want the cold-email subject-line playbook?

14-page PDF with 31 cold-email subject lines that hit 60%+ open rates, the 6 patterns that consistently outperform "Quick question," and the spam-trigger words modern filters quietly hate. Free, one email.

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100% client-side — your subject lines never leave your browser. Heuristics encode patterns from 200K+ cold emails analyzed in public open-rate research; not a substitute for actually shipping a small live A/B test.
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