Cold Email Subject Line Analyzer
Type a subject line and get a 0–100 score across length, spam triggers, capitalization, punctuation, and personalization — plus specific fixes. Everything runs in your browser.
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About this tool
Scores a subject line the way a first-pass human (and a spam filter) reads it: is it a sane length for a mobile inbox, does it contain the trigger words filters have been trained on for two decades, is it shouting, and does it look like it was written for one person or blasted to ten thousand? The weights favor what actually moves cold-email open rates — length and spam hygiene first, cleverness last. A high score doesn't guarantee opens; a low one usually explains the silence.
Nothing you type leaves the page. The spam word list and all scoring logic are plain JavaScript running in your browser — there is no server, no upload, and no logging of what you test.