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Subject line tester
Enter your subject line. Get an instant score across 12 deliverability factors, see how it looks in the inbox, and generate AI alternatives — no signup required.
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Inbox Preview
Desktop — 60 chars
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Mobile — 30 chars
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AI Alternatives
Enter a subject line, then generate alternatives.
Start typing to see your score
Real-time scoring
Your score updates as you type. No button press, no delay — instant feedback on every character change.
12 scoring factors
Every aspect of your subject is scored individually — length, spam words, format, sentiment, personalisation, and more.
AI alternatives
Not happy with your score? Generate three AI-written alternatives with a single click — each explained, each optimised.
Optimise every subject line, at send time
ForgeSend scores your subject lines live inside the campaign builder — plus spam checking, spintax, and full pre-send guardrails before every send.