Email Subject Line Tester

Find out if your email subject line will get opened

— before you hit send.

Paste any subject line and get an instant A–F grade,

score out of 100, and specific tips to improve it.

What you get:

- A–F grade + score out of 100

- Spam word detection

- Power word analysis

- Length check (mobile-optimised)

- Personalisation score

- Curiosity trigger detection

- 5 alternative subject line suggestions

- Save report as .json

Who it's for: email marketers, newsletter writers,

small business owners, copywriters.

Requirements: Python 3.8+ — no extra installs needed.