Email Subject Line Tester
Score subject lines for length, spam words & deliverability.
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Score
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Characters
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Words
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Emoji
Type a subject line to see its score and deliverability warnings.
The Email Subject Line Tester scores your subject line on length, word count, spam-trigger words, ALL-CAPS, excessive punctuation, and emoji use, then lists specific warnings so you can fix issues before you hit send. It's a fast deliverability and readability check that runs entirely in your browser — no account, no data leaves your device.
Built for
- Email marketers
- Newsletter writers
- Lifecycle & CRM teams
- Small business owners
What it includes
Deliverability score
A quick 0–100 score that combines every check into one signal of subject-line health.
Spam-word detection
Flags well-known trigger words and phrases that can push your email toward the spam folder.
Length & readability
Checks character and word counts against the mobile-friendly sweet spot so nothing gets cut off.
Caps, punctuation & emoji
Warns about shouting, exclamation overload, and emoji clutter that hurt trust and open rates.
How it works
- 1
Type or paste your email subject line.
- 2
Read the instant score and the stat strip (length, words, emoji).
- 3
Work through any warnings the tester lists.
- 4
Refine until you hit a clean, high-scoring subject line.
Frequently asked questions
What's the ideal email subject line length?+
Around 28–50 characters reads best across inboxes — long enough to add context, short enough to avoid truncation on mobile.
Which words trigger spam filters?+
Hype and money words like 'free', 'buy now', 'guaranteed', '100%', and 'risk-free' are common triggers. The tester highlights any it finds in your subject.
Do emojis hurt open rates?+
One well-placed emoji can help stand out, but several can look spammy or render poorly across clients. The tester warns when you use more than two.
Is the subject line tester free?+
Yes. It runs in your browser, needs no sign-up, and never sends your subject line anywhere.
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