Most subject lines get skimmed past in a crowded inbox. Paste yours and get an open-rate score out of 100 across hook, clarity, length, and deliverability, plus five stronger variants with matched preview text you can test today.
Open-rate score /100 · four levers · five stronger variants
Your subject line competes with dozens of others stacked in a crowded inbox, and it loses in a fraction of a second. Most subjects describe what the email is instead of giving the reader a reason to care, so the eye slides right past. On a phone, only the first 40 characters or so show before the line gets cut off, which means the hook has to land early or it never lands at all.
The subjects that win the open do a few things at once. They spark curiosity, but they stay relevant to what the reader actually wants. They read cleanly on mobile without truncating the point. And they steer clear of the spam triggers that quietly sink deliverability: all-caps, stacked punctuation, and money words that scream promotion. The grader scores all four levers and tells you which one is costing you opens.
One per line. Add optional context on the campaign or audience for a sharper read.
Hook, clarity and relevance, length and mobile fit, deliverability and trust.
Five sharper rewrites with matched preview text, ready to drop into your next test.
Your subject lines are sent to our server, processed once by the AI to generate the grade and variants, and not shared with anyone. We keep your email and a short usage summary so we can send you the results. Your subject lines are not resold, published, or used to train anything.
The score grades your subject lines against email best practices, not your list's actual behavior. It cannot see your sender reputation, your audience, or your past opens, and those move open rates too. Treat the score as a diagnosis and the variants as your test list, then measure them against your own sends.
Yes. Paste one subject line per line and the grader scores each one, then hands you five stronger variants across the batch. Pasting a few at once is the fastest way to see which angle wins before you send.
Yes. The deliverability check flags all-caps, excess punctuation, spammy money words, and misleading hooks that hurt inbox placement and trust. It is a copy-level check, not a full spam filter test, so pair it with a seed test on your own domain.
A strong subject line wins the open, but the click still lands on a page that has to close. We build product pages engineered around one number: revenue per visitor. Watch the demo and see the difference between a page that describes and a page that closes.
Watch the Demo → A few minutes, real pages, real numbers. No call required to watch.