Let’s be honest, coming up with fresh, engaging email subject lines is hard.

You can write the best newsletter in the world, but if your subject line doesn’t grab attention, no one will open it.

That’s why I started using an email headline generator, a tool designed to help create engaging subject lines and boost email open rates.

After testing multiple generators, I found the ones that actually work—and one that outperformed the rest.

Here’s everything I learned and the best email headline generators I recommend.

Why I Started Using An Email Headline Generator

Your subject line is the first impression of your email. It determines whether a reader opens, ignores, or marks it as spam.

I struggled for a long time to write subject lines that felt fresh, compelling, and clickable. Sometimes, I’d try to be clever—only for my open rates to drop. Other times, I’d play it safe, but my emails wouldn’t stand out.

That’s when I started using an email subject line generator to test different formats, styles, and emotional triggers, and it completely changed my approach.

The Best Email Headline Generators I’ve Tested

There are AI-powered tools, free generators, and premium options available. I tested a mix of these and found three types of tools that work best.

1. AI-Powered Tools for Instant Subject Line Ideas

AI-driven email headline generators analyze past high-performing subject lines and generate suggestions based on proven formulas. Here are the best ones I tried:

HubSpot’s AI Subject Line Generator – Uses AI to create multiple subject line variations.

Mailmeteor’s Subject Line Tester – Analyzes subject lines for engagement and spam triggers.

Stripo’s AI Subject Line Generator – Great for bulk subject line creation.

💡 Best for: Marketers who want quick AI-driven subject lines with a data-backed approach.

2. Free Email Headline Generators That Work

If you’re looking for free options, there are solid choices that provide engaging subject lines without a subscription.

Reply.io’s Cold Email Subject Line Generator – Specializes in subject lines for cold outreach.

AWeber’s Subject Line Generator – Offers creative suggestions based on different styles.

💡 Best for: Small businesses and creators who need free but effective subject line ideas.

3. The Generator That Gave Me The Best Results

After testing multiple tools, the one generator that consistently gave me the best results was beehiiv’s subject line testing and optimization feature that allows you generate subject lines directly in the editor before you send an email.

• A/B Testing Built-In – Allows you to test different subject lines and see what performs best.

• AI-Enhanced Suggestions – Generates subject lines based on your content.

💡 Best for: Newsletter creators and email marketers who want real-time data on what works best.

What I Learned From Testing Different Headline Generators

Common Patterns in High-Performing Subject Lines

After testing different tools, I noticed some consistent patterns in clickable subject lines:

• Curiosity Triggers – “You Won’t Believe What We Found”

• Urgency & Scarcity – “24 Hours Left to Claim Your Spot”

• Personalization – “John, Here’s Your Exclusive Offer”

• Number-Based Headlines – “7 Email Hacks You Need to Try”

The Mistakes I Made With Headlines That Didn’t Work

Not every subject line performed well. Here’s what hurt my open rates:

• Being too vague – “Check This Out” (People need a reason to click.)

• Overusing clickbait – “Shocking Secrets Inside” (Sounds spammy.)

• Too long – “Here’s Everything You Need to Know About Email Marketing in 2025” (Gets cut off on mobile.)

How A/B Testing Helped Me Find the Best Headlines

The biggest lesson I learned? A/B testing is everything.

By testing two different subject lines for the same email for my personal newsletter, I discovered:

• Personalized subject lines increased open rates by 22%.

• Urgency-based subject lines led to a 15% boost in engagement.

• Shorter subject lines (under 50 characters) performed best on mobile.

Why beehiiv Is The Best Choice For Email Headline Optimization

If you’re serious about improving your email open rates, you need a platform that lets you test, optimize, and track subject line performance.

beehiiv’s subject line optimization tools give you:

• Built-in A/B testing to see which subject lines perform best.

• Real-time engagement tracking so you know what works.

• AI-powered suggestions tailored to your audience.

💡 If you want the best subject line performance, start using beehiiv today.

Final Thoughts on Email Headline Generators

An email subject line can make or break your campaign. After testing multiple tools, I found that:

• AI generators help with quick ideas, but A/B testing is the real game-changer.

• Personalization, urgency, and curiosity make subject lines more engaging.

• beehiiv’s built-in tools are the best option for real-time headline optimization.

• Want to improve your subject lines and boost open rates?

🚀 Sign up for beehiiv today and start testing better headlines!

FAQ: Email Headline Generators

What is an email subject line generator?

An email subject line generator is a tool that creates clickable subject lines to boost open rates.

How do AI email subject generators work?

AI generators analyze high-performing subject lines and suggest variations based on best practices.

What’s the best way to improve my email subject lines?

Use a headline generator, run A/B tests, and analyze what works best with tools like beehiiv.