The subject line is the whole game for an email. Same body, different subject, completely different open rate — and most campaigns ship the subject on a hunch because writing and scoring several takes longer than the deadline allows.
I built SubjectLab for the A/B test you keep meaning to run but never set up.
30-second takeaway
- The subject line is the only part most recipients ever decide on.
- A brief → 6-8 variants with length and spam-risk scores, in one pass.
- Scoring before sending beats arguing about it in a thread.
The hunch that ships
Teams pick one subject line because producing five and comparing them is a project. So the highest-leverage decision in the campaign gets the least thought, and the open rate pays for it. The spam-risk score is the part nobody checks until a provider throttles them.
Generating variants with scores turns the hunch into a small, comparable set — pick by evidence, not by who spoke last.
What the tool does
Turn a campaign brief into 6-8 email subject variants with length and spam-risk scores. For indie marketers who A/B before they send. Open it and try — no signup.
SubjectLab runs in the browser, no account, no key.
FAQ
What is SubjectLab?
A tool that generates scored email subject-line variants from a campaign brief. No account, no key.
Does it send the email for me?
No. It gives you variants and scores; you pick and send through your own provider.
Will the spam-risk score guarantee deliverability?
It flags risky patterns; deliverability depends on your sender reputation too. It's one input, not a promise.
Author's Process
This product was built with AI coding tools. The discipline was scoring, not just generating — the scores are the feature.
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