Free Tool

AI Email Subject Line Generator

Get 10 high-CTR subject lines per email, each in a different angle, ready to A/B test.

What makes a great email subject line?

The subject line is your email's headline. It is the single biggest lever for open rate — typically a 3-5× difference between a great subject line and a generic one for the same audience. The principles:

  • Under 50 characters. Mobile email apps truncate around 40-50 chars. The full message has to fit there.
  • Curiosity beats clarity. “Your monthly report is here” vs “We found something odd in your numbers”.
  • Specificity beats vagueness. “3 things we shipped this week” outperforms “Our updates”.
  • Avoid spam triggers. ALL CAPS, “FREE”, $$$, exclamation marks!!! all hurt deliverability.
  • Personalisation helps, but only if it's genuinely relevant (the recipient's first name in the subject lifts opens 26%).

Why generate 10 variants?

Subject line performance is hard to predict. The InsiteChat AI Email Subject Line Generator returns 10 angles — curiosity, benefit, urgency, personalisation, question, number, pattern interrupt, social proof, FOMO, and imperative — so you can A/B test the top 2-3 with your audience and keep what wins.