Subject line analyzer

Score any subject line for length, spam triggers, personalization and clarity — and see exactly what to fix.

Free · No signup · Runs in your browser

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Your subject line

Aim for 30–50 characters, one clear idea, light personalization and zero spam words.

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100/ 100

Excellent

Working

About subject lines

What makes a subject line work

Short enough to render fully on mobile, long enough to carry one clear idea.

A first name or company reference lifts opens — without tipping into gimmicky.

Free, guarantee, act now and friends trigger filters and erode trust. Cut them.

FAQ4 entries

Still curious? Our team responds in under an hour.

Around 30–50 characters. Under 20 feels thin; over 60 risks truncation on mobile, where most email is opened.

Sometimes, sparingly. They can stand out in cold outreach but feel salesy if overused — test before committing.

We start at 100 and deduct for spam words, ALL-CAPS, excessive punctuation and poor length, while rewarding personalization, numbers and questions.

Questions can drive curiosity and opens, especially in cold email — just keep them specific and relevant to the prospect.

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Beyond the free tool

Data, warmup, multichannel sequences and AI — one platform, free for 7 days.

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