Email Subject Line Analyzer
Score any email subject line from 0-100 with a local rule engine: length, spam words, personalization, emoji and urgency dimensions, an A+ to F grade and concrete suggestions. Fully offline, nothing is uploaded.
FreeOnline Tool
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How to Use
- Type or paste a subject line; results update live.
- Check the overall grade (A+ to F) and total score (0-100).
- Review the five dimension bars: length, spam words, personalization, emoji and urgency (20 points each).
- Any hits from the built-in spam word list are shown as tags.
- Read the suggestions list and refine your subject.
- Click the good/bad sample buttons to see how scoring differs.
Features
- Local rule-based engine: instant scoring with no network calls and no AI API; subjects never leave the browser.
- Five 20-point dimensions: length (ideal 40-60 characters), spam words, personalization tokens, emoji count and urgency/curiosity words.
- Built-in Chinese and English spam dictionaries (free, limited, click here and more); hits are listed individually.
- Automatic penalties for ALL-CAPS words (-10) and multiple exclamation marks, with warnings.
- Final grade from A+ to F and a reproducible score from 0 to 100.
- Character and word counts plus per-dimension explanations and actionable suggestions.
- Six sample subjects (3 good, 3 bad) for comparison.
Use Cases
Pre-send marketing QA
Check subjects for spam triggers before sending to reduce the risk of landing in spam folders.
Product notification optimization
Validate length and personalization to lift open rates on transactional mail.
Team training
Compare good and bad samples with scores to teach subject line best practices.
A/B test pre-screening
Score candidate subjects locally before spending test rounds on weak ones.
Everyday business email
Quick self-check on tone and length before hitting send.
FAQ
Is this AI analysis?
No. It uses a built-in rule engine (length, spam dictionary, personalization tokens, emoji and urgency words). It is fully offline and never uploads your subject.
What are the scoring dimensions?
Length, spam words, personalization, emoji and urgency, 20 points each, with extra penalties for ALL-CAPS and exclamation marks, totaling 100.
What subject length scores best?
40-60 characters displays well on most mobile clients; below 20 or above 80 characters loses significant points.
Which words are in the spam dictionary?
Common Chinese and English marketing words such as free, limited, buy now, guaranteed and 100%; each hit is listed separately.
Is the score objective?
The grade is computed deterministically from the rules, so the same subject always scores the same; use your business judgment for the final call.