Free Email Subject Line Optimizer
Like SendCheckup, But $0
Analyze your subject lines for spam triggers, power words, and readability. Get an optimization score in seconds.
SendCheckup charges $29/mo for this
Stop paying $29/month for subject line analysis. This tool is free forever — no account, instant results.
Your data never leaves your browser. Everything runs client-side.
30-day no-questions refund promise: If it doesn't work for you, we'll refund you.
🔒 Your data never leaves your browser
Why writers choose us
Privacy First
Everything runs in your browser. Your subject lines and email lists never leave your device.
Instant Analysis
Get a full optimization score in seconds. No signup, no waiting, no queue.
Copy & Download
One-click copy to clipboard or download as .txt. Ready to paste into your email tool.
Pro Mode (Free)
Toggle to Pro mode for watermark-free output — no payment required.
Spam Trigger Detection
Flags words and phrases that trigger spam filters. Avoid the junk folder.
Power Word Analysis
Identifies power words that boost open rates and emotional engagement.
Ready to optimize your subject lines?
Join marketers who analyze their subject lines here instead of paying for SendCheckup.
Analyze Your Subject Lines — It's Free