Snippetbar logoSnippetbar
Try itBuy

Email subject line generator

Paste your email, newsletter or announcement, and get subject lines that each test a different reason to open. They're written from what's actually inside, so they don't overpromise.

Try an example

This is the Subject Line snippet. In Snippetbar, copy your draft in any email tool and get subject lines before you hit schedule.

Email subject line examples

Newsletter

Input

Why we killed our free plan, the 3 metrics we watch weekly, a customer interview template.

AngleSubject line
CuriosityWhy we killed our free plan
Specific3 metrics we check every Monday
BenefitA customer interview template you can steal
DirectFree plan, weekly metrics, interview template
✗ Avoid🚀 This week's AMAZING newsletter!!!

Product launch

Input

Snippetbar 2: inline rewrite, model switching, prompt chaining. 50% off for existing customers this week.

AngleSubject line
NewsSnippetbar 2 is here
BenefitRewrite text in place, in any app
Offer50% off Snippetbar 2 (this week, for you)
CuriosityThe update we've been using internally for months

Internal

Input

Performance reviews due Friday. Self-reviews first.

AngleSubject line
DirectAction needed: self-review due Friday
SpecificReviews: self by Fri, managers next week

How to write subject lines that get opened

  • Test angles, not synonyms

    “Why we killed our free plan” and “3 metrics we check every Monday” are different bets on what your reader cares about. A/B test angles and you learn something.

  • Keep the promise small and true

    The subject line only has to earn the open, and the email has to deliver on it. Overpromising gets opens once and unsubscribes after that.

  • Put the important words first

    Mobile inboxes cut subject lines off early, so lead with the part that matters.

  • Specific beats clever

    Numbers, names and concrete outcomes stand out in an inbox full of vague teasers.

  • Use preview text as a second line

    It sits right under the subject line. Use it to add information, not to repeat the subject.

  • Go easy on emoji, caps and “!!!”

    They can look spammy to readers and to filters. One emoji can work for a consumer brand, but rarely for B2B.

The snippet

This is the exact prompt the tool above runs. Save it as a snippet in Snippetbar and it works on any text you select.

Write email subject lines for the email below. Type: {newsletter | launch | sales | internal}.

Rules:
- 6 options, each testing a different angle: Curiosity, Specific (number/detail), Benefit, Direct, Offer (only if the email has one), Personal.
- Every line must be true to the email's content. No clickbait, no invented offers or urgency.
- Aim for under 50 characters; show the count.
- No all caps, no "!!!", max one emoji and only if the email's tone is casual.
- For each, add a preview text (under 90 characters) that complements rather than repeats.

Return a table: Angle | Subject | Preview text | Chars.

Use it where you work

  • In your newsletter tool

    In Substack, Beehiiv, ConvertKit or Mailchimp, copy the finished draft and pick two angles to A/B test.

  • For launch announcements

    Paste the changelog and get subject lines for customers, the waitlist and past buyers.

  • For internal comms

    Make the ask obvious in the subject line so people don't have to open the email to know what's needed.

More snippets

All snippets →

Questions

Run it in any app

Select the text, pick Subject line generator from the menubar or press its shortcut, and the result replaces it in place.

The subject line is the first thing anyone reads, so write it with care.

Snippetbar runs your snippets on anything you copy, in any Mac app. $29, one-time purchase.

Try itGet it today