A free tool from Zentor
Describe your email in a sentence or two and get five subject lines in five different styles. Free.
Zentor drafts replies and follow-ups inside your Gmail, in your voice — you approve before anything sends.
Your monthly newsletter for store owners is about cart abandonment. The subject line decides whether anyone reads it.
You typed
Monthly newsletter for ecommerce store owners. This issue covers reducing cart abandonment, with three case studies.
You're asking a former manager to be a reference. It's a favour — the line has to ask without being pushy.
You typed
Emailing a former manager to ask if she'd be a reference for a job I'm applying for.
Dark mode and offline sync just shipped — the two features customers asked for most.
You typed
Telling existing customers we launched dark mode and offline sync — the two most requested features.
Zentor drafts whole emails in Gmail — subject, body, follow-up — in your voice, then waits for your approval. For one-off lines this tool is enough; for the everyday inbox, hand it the thread.
See the AI email assistantAn email subject line generator exists because of a brutal little statistic of inbox life: your email competes with dozens of others for a glance that lasts under two seconds. The subject line isn't a title for the email — it's the advertisement for it. A great email behind a weak subject is a great email nobody reads.
The mistake most people make is writing the subject last, as a label: "Update", "Question", "Checking in". Those describe the email; they don't sell the open. Good subject lines give the reader a reason that belongs to them — a benefit, a curiosity gap, or a question they want answered.
An AI subject line generator earns its keep by handing you options you would not have written yourself, so you are choosing between angles instead of polishing one.
This subject line generator deliberately returns five different styles instead of five versions of the same idea, because the right lever depends on the reader:
Match the style to the relationship, not to your taste. The line you'd click isn't always the line your reader will.
Deliverability is boring until it isn't. The generator follows the baseline rules, and so should any line you write by hand:
Emoji are a maybe: one relevant emoji can lift opens in consumer newsletters, none belong in business mail.
If you write emails at any volume, the subject line stops being the bottleneck — the inbox is. Zentor's AI email assistant drafts replies and follow-ups inside Gmail in your voice: the subject, the body, and the remembering to send it, all before you ask.
Five options is only useful if you can pick one. A fast way to decide:
First, ask what the reader already knows. A colleague waiting on your answer needs the direct line; a stranger needs a reason to care, which pushes you toward benefit or curiosity. Second, ask what the email costs them to open. Low-stakes mail can carry a playful line; anything involving money, deadlines or bad news wants the plain one. Third, read the candidate next to your sender name — the two are always seen together, and a subject that repeats your name or company wastes its scarcest resource.
When two lines still tie, send the shorter one.
Yes, the generator is free. Generate opens Zentor, where you sign in or start a free trial and the subject lines are written for you.
Yes — Generate hands off to Zentor, where you sign in or start a free trial and the subject lines are drafted for you.
Because different styles win with different readers — direct for colleagues, curiosity for newsletters, a question for follow-ups. One line is a guess; five styles let you match the reader.
The constraints are built in: five lines in five named styles, each under 60 characters, no spam patterns — instead of hoping the chatbot remembers your rules every time.
They follow what works — concrete, short, reader-focused — but your list and sender reputation matter more than any single line. Take two candidates and A/B test if your mail tool supports it.
All caps, repeated exclamation marks, classic spam words ('free', 'guaranteed', 'act now'), and bait that doesn't match the email. The generator avoids all of them.
Regenerate — each run produces a fresh batch. Or describe the email differently (mention the audience or the offer explicitly) for a different angle.
Yes, that's a common use — describe the issue or campaign and its audience. For one-off business emails it works the same way.
Describe the email in general terms — you don't need to paste the body or real recipient details. See the privacy policy for how Zentor handles data.
