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About this tool
Score email subject lines for spam risk, readability, urgency and clickability, preview inbox truncation across Gmail, Outlook and Apple Mail, and A/B test two subject lines side by side.
Email Subject Line Tester is a free marketing & social tool that runs entirely in your browser — nothing to install, no account to create, and your data never leaves your device. Open the page, add your input, and get a clean, copy-ready result in seconds.
Open Email Subject Line Tester on AltFTool — it loads instantly in your browser.
Add your input to the workspace.
Adjust the options until the result looks right.
Copy or download the output and put it to work.
A focused workspace for one-off content, data, or planning jobs — open it, use it, done.
Start with a rough input and iterate until the result matches exactly what you need.
Copy or download the output for your project, document, or daily workflow.
Yes — Email Subject Line Tester is completely free on AltFTool, with no signup, no trial limits, and no hidden costs.
Yes. Email Subject Line Tester runs in your browser, so what you enter or upload stays on your device instead of being sent to a server.
Score email subject lines for spam risk, readability, urgency and clickability, preview inbox truncation across Gmail, Outlook and Apple Mail, and A/B test two subject lines side by side. It's built for quick, everyday marketing & social tasks with results you can copy or download straight away.
Yes — Email Subject Line Tester works in any modern browser, on desktop, tablet, and mobile, with the same features everywhere.
