Automizy’s Subject Line Tester grades your subject line and provides a score on how good your subject line is and how well it would perform in an inbox.
It’s simple to use, once you write your subject line, you’ll instantly see how it scores.
Bonus Tip
If you’re undecided between 2 or more subject lines, I recommend you to AB test your variations and let the data decide on which subject lines perform the best.
If you’re curious, here is an article on how Automizy’s Subject Line Tester works.