Ever put days into an email campaign and watched your subject line flop? That sinking feeling when no one opens your email hits hard. I remember the first time I tried to fix low open rates. I changed the subject line five times. Nothing worked. Then I tried out an AI email subject line generator—and open rates shot up almost overnight. If you feel stuck or want better results fast, you’re in the right spot. This guide covers seven AI-powered tools that leverage subject line optimization, helping marketers and teams triple their open rates without guesswork.
Why Email Subject Lines Matter (More Than You Think)
You only get one shot to grab attention in an inbox. About 47 out of 100 people open emails just for the subject line. At the same time, 69 out of 100 will send your email to spam if the subject feels off. So all that hard work on content is wasted unless you get the subject right. That’s why picking the right tool, like an AI email subject line generator, is so important.
1. Copy.ai – Fast, Smart Personalization for Any Brand
Copy.ai uses advanced machine learning to write catchy, creative subject lines. It pulls top data trends from millions of emails. You pick your goal, add a bit about your offer, and Copy.ai gives you smart line options that aid in subject line optimisation.
- Best for: SaaS teams, e-commerce brands, busy marketers.
- How it works: Pick a goal (promo, update, sale), add keywords, and let it suggest lines. [Insert screenshot of Copy.ai interface]
- Sample subject lines:
- Your Exclusive Offer Inside
- Unlock Savings—Limited Time Only!
- Did You Forget This?
- Pros: Fast, easy to use, lots of integrations, real-time A/B test tips built in.
- Cons: Some advanced options need a paid plan. Sometimes repeats themes.
- Pricing: Free trial, then plans start at $36/month. See pricing
2. Jasper – Power and Flexibility for Marketers
Jasper stands out for deep personalization and tone control. It asks for your target audience and brand voice, then shapes subject lines to fit, supporting email marketing AI strategies.
- Best for: Marketing agencies, SaaS, brands with varied audiences.
- How it works: Set your tone (fun, formal, bold), add details, and Jasper gives you three or more options. [Insert Jasper workflow screenshot]
- Sample subject lines:
- Meet Your Next Big Win
- Unlock What You Missed
- This Week’s Insider Tip
- Pros: Easy A/B testing support, works for B2B/B2C, export features.
- Cons: Takes a few minutes to set up; higher price for teams.
- Pricing: Starts at $39/month after free trial. See pricing
3. ChatGPT (OpenAI) – Versatile for Custom Prompts
ChatGPT can write almost any type of subject line if you ask with the right prompt. It’s not built for email, but it adapts fast and keeps learning, acting as an AI subject line tester.
- Best for: Small businesses, marketers who like to test lots of ideas.
- How it works: Type a prompt (like “write a subject line for a spring sale email to parents”). You get instant ideas. [Insert ChatGPT prompt example screenshot]
- Sample subject lines:
- Spring Deals—Don’t Miss Out!
- Parents: Your Guide to Spring Savings
- Unlock Early Access Today
- Pros: Flexible, free tier, supports detailed custom work.
- Cons: Needs manual review for compliance, no built-in analytics.
- Pricing: Free for most, plus plans from $20/month for GPT-4.
4. Smartwriter – Laser-Focused on Personalization
Smartwriter uses AI to research your audience and even checks LinkedIn or your website to add custom touches. It is great for cold outreach or sales, significantly helping to increase email open rates.
- Best for: Sales teams, B2B, cold email campaigns.
- How it works: Enter your contact list, set the message goal, and Smartwriter builds unique subject lines. [Insert Smartwriter subject line example]
- Sample subject lines:
- John, Ready to Grow Your Sales?
- Your Next Move in [Industry]
- Let’s Talk Opportunities
- Pros: Deep personalization, strong for lead gen, automates a lot.
- Cons: Best with existing contact details, higher price for scale.
- Pricing: Starts at $49/month. See pricing
5. Anyword – Predicts What Will Work Best
Anyword uses real performance data and gives a “score” for each generated subject line, showing the most likely to succeed. Great for teams that want to see proof before sending, aiding in subject line optimisation.
- Best for: Marketers who want data and split-testing built in.
- How it works: Paste your email or goal, and Anyword shows subject lines with performance scores. [Insert Anyword score screenshot]
- Sample subject lines:
- Unlock Your Bonus Deal Now
- Ready for a Better Solution?
- Your Guide to Big Results
- Pros: Score-based, fast results, built-in analytics.
- Cons: Limited free plan, best value for teams or big lists.
- Pricing: Free trial, then plans start at $49/month. See pricing
6. Phrasee – AI That Learns Your Brand Voice
Phrasee focuses on using your data and brand to write lines that stay true to your voice. It learns from previous email results and adapts to help increase email open rates.
- Best for: Big brands, companies with strict brand rules.
- How it works: Connect your email account. Phrasee studies past subject lines and tests new ideas. [Insert Phrasee dashboard screenshot]
- Sample subject lines:
- Discover What’s Next for You
- Your Daily Update Awaits
- See the Future of [Your Industry]
- Pros: True brand fit, adapts over time, strong analytics.
- Cons: Not best for small budgets, needs a brand style to start.
- Pricing: Custom quotes only. See details
7. MailerLite AI Subject Line Generator – Simple and Free For Starters
MailerLite adds a free tool to help marketers and solopreneurs get started with AI email subject line ideas. It is simple and fast, with no login needed. This tool is a great introduction to email marketing AI.
- Best for: Small business owners, side hustlers, beginners.
- How it works: Type your topic or main offer, and MailerLite gives back five ideas each time. [Insert MailerLite subject line generator screenshot]
- Sample subject lines:
- Your Weekend Savings Are Here
- Big News for Small Businesses
- Unlock the Next Step
- Pros: Free, no signup, very easy for quick jobs.
- Cons: Fewer options than paid tools, less customization.
- Pricing: Free to use from the website. Try now
What Makes a Great AI Subject Line Generator?
- Real AI that creates, not just copies, subject lines from templates.
- Lets you set tone, length, and add main keywords for fit.
- Easy A/B testing features for better results.
- Keeps subject lines CAN-SPAM safe and legal.
- Works for your industry and campaign goals.
[Insert Visual Checklist: Dos and Don’ts of AI Subject Line Generators]
How to Use an AI Email Subject Line Generator: Step by Step
- Pick your goal (promo, newsletter, welcome).
- Set your audience and pick a tone.
- Enter your top keywords or product focus.
- Check the subject lines the tool creates.
- Pick your favorites, then A/B test them with real users.
- Review your data and try again for the next campaign.
[Insert quick video walkthrough of using a subject line generator]
Common Mistakes to Avoid
- Using AI lines without A/B testing them.
- Not matching your brand’s real voice.
- Piling on emojis or urgent words (hurts deliverability).
- Ignoring legal checks—stay CAN-SPAM compliant.
- Not checking how it looks on a mobile phone.
FAQs
How do AI subject line generators work? They use machine learning and test results from millions of emails to predict what words get more opens, vital for subject line optimization.
Are these tools free? Most have a free trial or basic plan. The best features, like analytics or personalization, need a paid plan.
Do AI subject lines really beat ones people write by hand? In tests, AI lines often win for big batch emails. But for one-time sends, human touch can still help.
What data should I give the tool? Provide a clear topic, keywords, and who your audience is. The more details, the better the ideas.
Final Tips and Next Steps
Now you’ve seen the top AI email subject line generators for 2024. Pick your favorite and try it out—most offer free or low-cost trials. Always A/B test every subject line. Watch the open rates, try the next best idea, and keep improving. Want a hands-on demo or more real-world tips? Click below to get started with your AI email subject line generator today.
Try It Yourself
Ready to see your open rates triple? Pick an AI email subject line generator from this list and test it on your next email campaign. For more tips or live walkthroughs, join our weekly newsletter or sign up for a free demo to witness firsthand the benefits of AI in email marketing!