Score any subject line on length, spam words and personalization — or generate high-open ideas. \ Free, with no signup.
Test a subject line
…or generate ideas
Score any cold email subject line on length, spam words and personalization — or generate new ideas. Free, in your browser.
Paste a subject line
Drop in the subject line you want to test.
Get a score
See a 0–100 score with specific, actionable tips.
Or generate ideas
Enter your topic to generate high-open subject lines.
A/B test for real
Run the best ones in a cold email campaign.
Your subject line decides whether a cold email is opened or ignored — and whether it lands in the inbox or spam. Yet most are too long, too salesy, or stuffed with trigger words.
This tool scores any subject line on length, word count, spam-trigger words and personalization, then tells you exactly what to fix. Stuck for ideas? Generate proven formats in one click.
A great subject line only matters if the email reaches a real inbox. Verify your recipients and keep your copy clean to protect deliverability.
Emailchaser lets you A/B test subject lines across a campaign and sends follow-ups automatically — so you learn what actually gets replies.
What makes a good cold email subject line?
Keep it short (3–9 words, under ~50 characters), make it specific and personalized, avoid spam-trigger words and ALL CAPS, and spark curiosity. A relevant question often lifts opens. This tool scores your subject line on exactly these factors.
How long should a cold email subject line be?
Aim for under about 50 characters so it isn't cut off on mobile, and roughly 3–9 words. Shorter, specific subject lines consistently outperform long or salesy ones.
Why do my cold emails go to spam?
Spammy subject lines are a common cause — words like 'free', 'guaranteed' and 'act now' raise your spam score. The tester flags these. Deliverability also depends on a clean list and an authenticated sending domain.
Is the subject line tool free?
Yes — it's free, needs no signup, and both the tester and generator run entirely in your browser.
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