Free Cold Email Subject Line Generator
Get 5 cold email subject lines that get opened — not deleted. Paste your cold email and the AI writes subject variants for prospecting, outreach, and sales follow-ups.
30+ cold email subject lines that work in 2026
A swipe file of proven cold email subject lines, organized by outreach angle. Replace {firstName} and {company} with real values.
Short & casual
- quick question
- worth exploring?
- one idea
- curious
- {firstName}?
Company-specific
- Noticed {company} just launched [X]
- About your [specific page/product]
- {company}'s new [feature/initiative]
- Saw {company} is hiring for [role]
- {company} + [us] — worth 10 min?
Trigger-based
- Congrats on the Series B
- Saw your post on [topic]
- Your talk at [event] last week
- Following up on [announcement]
- After reading your [article/post]
Problem/outcome
- How [similar company] solved [problem]
- Cut [metric] by 40% at [similar company]
- For the [specific pain point] problem
- Re: [their KPI] — small idea
- [Outcome] without [cost]
Referral / intro-style
- [Mutual contact] suggested I reach out
- Intro via [mutual connection]
- Following [mutual contact]'s suggestion
- Heard you from [person/event]
- [Person] mentioned you might be open to chat
Question-led
- Is [assumption] true at {company}?
- Are you the right person for [topic]?
- How are you handling [specific problem]?
- What's your current [workflow/tool]?
- Who owns [function] at {company}?
Cold email subject line best practices
Short wins in cold email
The best-performing cold email subject lines are 2–7 words. Shorter subjects look like real 1-to-1 messages from a colleague. Long, marketing-style subjects trigger pattern-matching in your prospect's brain: this is a sales email, delete.
Specificity beats cleverness
Reference something specific to the prospect: their company, a recent launch, a hiring page, a podcast appearance. Specificity signals effort. "Quick question about your recent Series A" beats "Loved your post" every time.
Avoid sounding like a template
If your subject line could apply to 1,000 prospects, it's a template. Swap "Scaling your sales team" for "Your 3 SDR hires this quarter." Swap "Your marketing" for "The landing page you shipped last week."
Match subject to sender
Sending from a founder's personal email? Use casual subjects: "quick question." Sending from an SDR? Slightly more descriptive works. Match the subject tone to who is sending.
Need more than a free tool?
Like cold email subject line generator? The Aeralis Gmail add-on does this and more, right inside your inbox.
Free tier includes 15 emails/month. No credit card required.
Frequently Asked Questions
Common questions about our cold email subject line generator
What makes a good cold email subject line?
Good cold email subject lines are specific, low-pressure, and sound like a 1-to-1 message from a human. Avoid anything that sounds like a blast. Subject lines mentioning the recipient's company, recent news, or a specific observation consistently outperform generic templates.
What is the average cold email open rate?
Industry benchmarks (Lemlist, Woodpecker, 2024 data) put good cold email open rates at 40–60%. Anything below 30% suggests your subject line or sender reputation needs work. The top 10% of cold email campaigns hit 70%+ opens.
How long should a cold email subject line be?
Keep cold email subject lines under 50 characters — ideally 3–7 words. Short, casual-sounding subjects consistently outperform long descriptive ones in cold outreach. "Quick question" and "{firstName}, one thought" style subjects beat marketing-style subjects.
Should I use personalization tokens in cold email subject lines?
Yes, but only if they look natural. First name, company name, and references to recent activity (a LinkedIn post, product launch, fundraise) lift open rates significantly. Avoid generic tokens like "{firstName}, check this out" — it signals automation.
What cold email subject lines trigger spam filters?
Avoid: "FREE," "GUARANTEED," "ACT NOW," "LIMITED TIME," "WINNER," "URGENT," excessive punctuation, ALL CAPS, and any subject with more than one emoji. Also avoid symbols like $$$ or %%. Modern spam filters (Gmail, Outlook, Apple Mail) score these heavily.
Can I use this for B2B prospecting and sales outreach?
Yes — that's the primary use case. It works for SDR outreach, founder-led sales, recruiting, and fundraising. Paste the body of your cold email and you'll get 5 subject line variants optimized for low-friction, high-curiosity opens.
Is this tool free?
Yes, completely free. You can generate up to 10 sets of cold email subject lines per hour with no signup, no credit card, no email required.
Looking for full cold email drafts? Try the Cold Email Personalizer or the general subject line generator.
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