AI Email Subject Line Generator
Describe your email, pick a type and tone, and get 12 subject lines written by AI. Each one is scored on the spot for length, spam triggers and power words, so you can see which to send and why.
Your 12 lines will land here, like an inbox.
Power words get highlighted, spam triggers get struck through, and each line gets a 0–100 score you can open in the tester.
How the score works
Every line is checked by the same open, rule-based analyzer that powers our subject line tester. It is not a prediction of your open rate, which depends on your list, sender reputation and timing. It is a checklist of the things you control in the subject line itself, turned into points.
| Factor | Points | What earns them |
|---|---|---|
| Length | 25 | 28–50 characters, so the whole line shows on a phone |
| Spam triggers | 20 | No phrases like “act now”, “100%”, “risk-free” |
| Power words | 15 | Specific, emotional or curiosity words |
| Formatting | 15 | No ALL CAPS, stacked !!! or emoji clutter |
| Word count | 10 | 4–9 words |
| Personal | 8 | “You”, “your” or a merge tag |
| Specificity | 7 | A number, a question or a how-to |
Try it on one line
Edit the line below and watch the score move.
FREE!!! Act now, 100% guaranteed
Need a starting point?
Browse scored examples by campaign, or grab a ready-made email and personalise it with AI.
Subject line examples
- Catchy Email Subject Lines
- Sales Email Subject Lines
- Follow-Up Email Subject Lines
- Welcome Email Subject Lines
- Abandoned Cart Email Subject Lines
- Black Friday Email Subject Lines
- Newsletter Subject Lines
- Re-engagement Email Subject Lines
- Event Invitation Email Subject Lines
- Christmas Email Subject Lines
- Valentine's Day Email Subject Lines
- Cyber Monday Email Subject Lines
- Cold email subject lines
38 email templates
Frequently asked questions
How does the AI subject line generator work?
You describe the email, choose a type (newsletter, sale, cold outreach and more) and a tone. An AI language model writes 12 varied subject lines using different angles such as curiosity, a number, a question or a direct benefit. Your browser then scores each line with a transparent rule-based analyzer.
What is a good email subject line?
A good subject line tells the reader specifically what is inside and why it matters to them, in about 30–50 characters, without hype. “Your 20% off expires Sunday” and “The 3-minute fix for your Monday inbox” work because they are concrete.
How do you create email subject lines?
Start from the one reason someone should open, then write several versions using different angles: a benefit, a number, a question, curiosity, a personal “you”. Score them, keep the two strongest and A/B test them. The generator above does the first steps for you.
Can it write subject lines in other languages or with emoji?
Yes. Under “More options” you can choose a language (Spanish, French, German, Portuguese, Italian, Dutch or Polish), control emoji use, require a keyword such as your offer or brand, and add {first_name} merge tags.
Is it free? Do I need an account?
It is free and there is no sign-up. To keep the service fair there is a limit on how many generations you can run in a few minutes.
Does a higher score mean a higher open rate?
Not directly. Open rates depend mostly on who is on your list, whether they trust the sender and when you send. The score checks what you control in the line: length, clarity, spam-like wording and formatting. Use it to rule out weak lines, then A/B test the best two with your own audience.
What happens to the text I type?
It is sent to an AI model through Vercel AI Gateway to write the lines and is not stored by us. Your last input and any lines you save are kept only in your own browser. See the privacy page for details.
How many subject lines should I test?
For a typical list, A/B test two clearly different lines rather than many similar ones. Differences in angle (question vs. benefit, with or without a number) teach you more than swapping single words.