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subject-line-generator

subject-line-generator

github.com/victor-shulgaMarketing & growth146 installsUpdated 4d ago
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About subject-line-generator

A skill that generates and scores email subject-line options for cold email or LinkedIn InMail. It is for outbound writers who need varied angles and a ranked shortlist for testing.

Key features

  1. 01At least 12 subject-line options
  2. 02Six distinct pattern types
  3. 03Curiosity, specificity, and length scoring
  4. 04Ranked shortlist with top three flagged
  5. 05Angle variation for A/B tests
  6. 06Open-rate tracking guidance

Use cases

  1. 01Drafting subjects from an email and its signal
  2. 02Creating alternatives for cold email or InMail
  3. 03Selecting variants for an A/B test
  4. 04Reviewing subjects when open rates are low

Install

Copy the command and run it in a terminal.

$npx skills add https://github.com/victor-shulga/outbound-engine-skills --skill subject-line-generator

After installing, type/subject-line-generatorin Claude Code to confirm it loaded.

Details

From the project README

Subject Line Generator

Generate 10+ subject line options for a given email, score each one, and return a ranked shortlist for testing.

What you need

  • Email body (step 1 at minimum)
  • ICP and persona context
  • Signal the email is built around
  • Channel: cold email or LinkedIn InMail

Principles

  • Subject lines under 6 words perform best in cold outbound
  • Never use the company name in the subject line — it reads as a template
  • Curiosity beats clarity when it comes to cold email subject lines
  • Questions outperform statements when the question is specific, not generic
  • Personalization tokens work only when they're signal-derived, not just [First Name]

Subject line patterns to generate

Generate at least 2 from each pattern:

  1. Signal reference: directly references what just happened at their company ("new SDR team, new pipeline problem")
  2. Problem statement: names the specific pain without a solution ("pipeline that depends on one channel")
  3. Reframe: presents an assumption they hold and challenges it ("outbound isn't broken — the playbook is")
  4. Direct question: asks the exact question the email answers ("is your outbound tied to one channel?")
  5. Unexpected angle: something they wouldn't expect from a sales email ("your new CRO's first 90 days")
  6. Ultra short: 1–3 words, creates pattern interrupt ("quick thought", "SDR question")

Process

  1. Generate 2 subject lines from each of the 6 patterns above (12 total)
  2. Score each on: curiosity (0–2) + specificity (0–2) + length penalty if over 6 words (−1)
  3. Rank by score
  4. Flag top 3 for A/B testing

Output format

Subject lines: [hypothesis / email step]
Email: [step number and first line]

RANKED OPTIONS
Score | Subject line | Pattern
[n]   | [subject]    | [pattern type]
...

TOP 3 FOR TESTING
A: [subject]
B: [subject]
C: [subject]

Recommended default: [A/B/C] — [one-line reason]

Notes

  • Vary the top 3 by ANGLE, not by swapping synonyms — token-level randomisation changes nothing a filter reads and nothing a prospect notices. Different question, different fact, different frame.
  • Test subject lines systematically — track open rate by subject line variant, not campaign overall
  • If open rate is below 40%, subject line is the first thing to change before touching copy
  • Avoid: "quick question", "following up", "[First Name]" as opener — overused and filtered mentally

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