Free Tool
Cold Email Subject Line Tester
TL;DR
Free cold email subject line tester — paste your subject line and get a score for length, spam triggers, personalisation, and curiosity gap.
Cold Email Subject Line Tester
0 characters · 0 words
About this tool
Scores subject lines on four dimensions that correlate with open rates: length (3–8 words is optimal), spam trigger words, personalisation tokens, and curiosity gap signals. Runs locally.
How it works
- Paste your subject line. Type or paste the subject you're considering.
- See the score. Get scores for length, spam risk, personalisation, and curiosity gap.
- Iterate. Tweak based on the recommendations until you hit 80+.
How we built this
Built and maintained by the LemCoach team. All calculations run client-side — your inputs never leave your browser. Formulas are reviewed against industry benchmarks we collect from anonymised LemCoach session data each quarter.
Frequently Asked Questions
This tool scores your text. LemCoach scores your voice.
Practise a full cold call against an AI buyer and get live feedback on talk ratio, filler words and objection handling.
No credit card required · 7-day free trial · Cancel anytime
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