Free Email Subject Line Tester Tool
Score your subject lines for clarity, curiosity, and spam risk. Test email subject lines to improve open rates and ensure they avoid spam filters before sending.
Why Subject Line Testing Matters for Open Rates
Subject lines are the first thing recipients see and determine whether your email gets opened. Testing subject lines helps you create compelling, clear subject lines that improve open rates while avoiding language that triggers spam filters.
- Improve open rates by creating clear, compelling subject lines
- Avoid spam filters by identifying problematic language before sending
- Increase engagement by optimizing for curiosity and clarity
- Save time by catching issues before sending campaigns
- Optimize for mobile by ensuring subject lines display well on all devices
How Subject Line Testing Works
Our subject line tester analyzes multiple factors to provide comprehensive scoring:
- Length analysis: Checks if your subject line is optimal length for display across email clients
- Spam word detection: Identifies words and phrases that commonly trigger spam filters
- Clarity scoring: Evaluates how clear and specific your subject line is
- Curiosity assessment: Measures how engaging and compelling your subject line is
- Best practices check: Reviews capitalization, punctuation, and formatting against email best practices
The tester provides actionable recommendations to help you optimize your subject lines for both open rates and deliverability.
Related Free Tools
Improve your email copy and deliverability with these related tools:
Subject Line Tester FAQs
Automate Subject Line Testing in Every Campaign
Get automatic subject line testing and A/B testing for all your email campaigns with SuperSend. Test multiple subject lines and optimize for the highest open rates automatically.