Free Tool
Subject Line Checker
Test and optimize your email subject lines for maximum open rates and deliverability. Analyze length, spam score, and mobile previews instantly.
✓ Open Rate Prediction✓ Spam Score✓ Mobile Preview
0/60
Optimal: 30-50 chars
Why analyze your subject lines?
Length Optimization
Analyze character count to ensure your subject line isn't cut off on mobile devices.
Spam Score Analysis
Identify trigger words and formatting that might send your email to the spam folder.
Mobile Preview
See exactly how your subject line appears on iPhone and Android notification screens.
Open Rate Prediction
Get data-backed predictions on how well your subject line will perform.
Character Analysis
Monitor word count, special characters, and emoji usage for best practices.
A/B Testing Ideas
Get suggestions to create variations for split testing your campaigns.
✓ High-Performing Examples
- "Quick question about [Project]"
- "5 minutes to boost your sales by 30%"
- "Your invoice is ready, [Name]"
- "Last chance: 50% off ends tonight"
- "Free guide: Double your email opens"
✗ Avoid These Mistakes
- "URGENT!!! LIMITED TIME OFFER!!!"
- "Make money fast with this secret trick"
- "FREE FREE FREE - Click here now!"
- "Congratulations! You've won $1000"
- "RE: Important business proposal"
How to use this tool
1
Enter Subject
Type your email subject line.
2
Analyze
Get instant feedback.
3
Review
Check score & previews.
4
Optimize
Apply tips to improve.
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