Email Subject Line Tester — free online
You wrote the email, but the subject line is the part most people will ever see. Too long and the phone cuts it off. One wrong word and it lands in spam. We added a free tool that helps you check it before you hit send — Email Subject Line Tester — right in your browser.
What it does
You type your subject line and it shows you a mobile preview and a desktop preview, so you can see exactly where it gets trimmed on each. It also flags common spam-trigger words, so you can swap them out before they hurt your delivery.
Nothing leaves your device
Everything runs in your browser. Your subject line and your draft are never uploaded, never saved, and never seen by us. When you close the tab, nothing stays behind.
How to use it
- Open Email Subject Line Tester and type or paste your subject line.
- Check the mobile and desktop previews and look at the spam-word warnings.
- Tweak the wording until it reads well and is clean, then copy it into your email.
It's free with no limit. There are more small tools on the Apps page.