CEO
Cool App
Nice app
It's a nice app.!!
Great tool to get instant feedback on subject line
Helped me skip hours of back and forth, condensing production time dramatically.
Love it
Brilliant.
Great tool
Helps me achieve my open rates.
Archived App (Last seen on 16 May 2026)
This is an archived listing of the app previously available on the App Store.Although the app is no longer distributed by Apple, you can still view its description, screenshots, version history, ratings, and metadata for reference.
About
This free online tool helps marketers improve their email campaigns by testing subject lines. It analyzes over 900 rules to identify potential deliverability and marketability issues, aiming to boost overall campaign results.
✓Email subject line testing
✓Deliverability analysis
✓Marketability assessment
✓Over 900 testing rules
✓Free online marketing support
Show original description
What's New in Subject Line
3.9.1
January 25, 2021
· Over 10 Million Subject Lines checked via the SubjectLine.com tool · Updated rules to reflect the latest marketing research trends · Performance results based on 'Marketability' and 'Deliverability' · SubjectLine.com App now applies over 900+ unique rules
MoreUser reviews
FAQ
How does Subject Line grade email subject lines?
Subject Line applies over 900 unique rules to test your subject lines for potential deliverability and marketability issues that could impact campaign results. It aims to provide insights to improve your overall email campaign performance.
Is Subject Line free to use?
Yes, Subject Line is a free online marketing support tool. It has been used to test over 10 million subject lines and is ranked as the #1 free email subject line grading tool.
What devices does Subject Line support?
Subject Line is available on iPhone and iPod devices. It was last updated on January 25, 2021, with version 3.9.1.
What is the age rating for Subject Line?
Subject Line has an age rating of 4+. This indicates it is suitable for a broad audience.
Does Subject Line have ads?
Yes, Subject Line contains advertisements. As a free tool, it is supported by ads.
When was Subject Line first released?
Subject Line was first released on May 29, 2012. It has been providing marketing support for many years.
What is the user sentiment for Subject Line?
Subject Line has a high rating of 4.7 stars based on 6 ratings, indicating positive user sentiment.