Email Subject Line Tester
Free Email Subject Line Tester analyzes your subject lines for length, spam triggers, emotional impact, and effectiveness. Get instant scores and actionable suggestions to improve your email open rates. No signup required.
Test Your Subject Line
🔀 A/B Compare Subject Lines
Test two subject lines side by side to see which performs better.
📝 Subject Line Best Practices
📏 Length
- Keep it 30-50 characters
- Mobile shows ~30-40 chars
- Put key words first
- 5-7 words is ideal
🎯 Clarity
- Be specific, not vague
- State the benefit clearly
- Match content to subject
- Avoid clickbait
⚡ Power Words
- Exclusive, Limited, New
- Free, Proven, Secret
- Instant, Easy, Quick
- Use sparingly (1-2 max)
🚫 Avoid
- ALL CAPS (looks spammy)
- Too many !!! or ???
- Spam triggers (FREE!!!)
- Misleading claims
Subject Line Tester FAQ
What is an email subject line tester?
An email subject line tester analyzes your subject line for factors that affect open rates, including length, spam triggers, emotional appeal, and clarity. It provides a score and suggestions for improvement.
Is this subject line tester free?
Yes, completely free with unlimited tests. No registration or payment required. Test as many subject lines as you want.
What makes a good email subject line?
A good subject line is 30-50 characters, creates curiosity or urgency, avoids spam words, includes personalization when possible, and clearly communicates value to the reader.
How long should my subject line be?
Ideal length is 30-50 characters (5-7 words). Mobile devices show about 30-40 characters, while desktop shows 60+. Keep the most important words at the beginning.
Do emojis help subject lines?
Emojis can increase open rates when used appropriately - they add visual interest and personality. However, overuse or inappropriate use can hurt deliverability. Use 1-2 relevant emojis max.
What are spam trigger words?
Spam triggers are words that email filters look for, like "FREE", "ACT NOW", "LIMITED TIME", "WINNER". Using these excessively can send your email to spam folders.