The best email Subject Line Testers and generators to Increase your email results

Looking for the best email subject line tester? You’ve came to the right place.

Crafting the perfect email subject line isn’t as easy as you’d think; luckily there are a few great subject line testers out there that make things better. A good subject line is key to higher open rates and conversion.

Need more convincing?

  • Survey says that 35% of customers open emails based only on the subject line. A great subject line makes all the difference in open rates.
  • 69% of customers mark emails as spam based on the subject line. Too many spam complaints negatively influences your deliverability and sender reputation.

The perfect subject line is based on the knowledge you have of your recipients, plus the right balance of creativity, curiosity, and a whole lot of testing!

Luckily there are multiple subject line testing tools to come to our aid.

A subject line tester is a tool that helps you validate an aspect of your email subject lines. May it be impact on deliverability and spam filters, length and how it renders on mobile, or even predict the emotional impact and how well your subject lines will entice opens!

Let’s go through the 10 free subject line testers you can use to get your emails to bring higher results.

Writing subject lines is still part art and part science. There is a craft to it. Some of the tools are (way!) more sophisticated than others, but some of these subject line tools use data to come up and generate the best subject line tips.

1. Test Subject by Zurb

View your subject line on Mobile and devices

test subject email subject line tester

Most people decide to open their email based on the sender name and the subject line. Mobile email clients and devices often cut off your subject line or sender name, leading to sometimes funny, but often head scratching results.

Incomplete subject lines, sometimes make inappropriate sentences. So how does your subjectline look on mobile devices?

Test Subject by Zurb, is a mobile subject line tester that will show you exactly how you email subject lines on mobile look. Did you know that over half of emails are now opened on mobile? Give it a go and make sure your readers “get the message” on mobile clients.

2 Omnisend subject line tool

Test your subject lines and get tips to improve

omnisend email subject line tester

The Omnisend subject line tool gives your subjectline a (data-backed) score. The subject line tool evaluates your copy and alongside the subject line score recommends improvements. For instance here is an analysis of the “This is how you prepare a delicious meal”

email subject line score grader

It shows the length in characters and words as well as suggestions to replace spam-trigger words, style and readability.

3. Email Subject Line Tester from CoSchedule

Grade your subjectline text with preview

email subject line tester coschedule

CoSchedule is all about content marketing, but their email subject line tester is very helpful. Your mirco-copy is analysed and gets scored X out of 100. The goal is to make your copy seem more human and convert more.

Other things the Coscedule team looks at in your subject lines:

  • Words that increase opens from their own “word bank” Positive words should affect the open rate positively, while the negatives can hurt open rates.
  • Upper or lower case, which will work best for your subject line?
  • Character & word count.
  • Numbers and emoji: Did you use any emoji, numbers anyone?

The tool also gives you a limited preview of how the subject line will look on desktop and mobile.

4. Accessible Email

Test the accessibility so everyone can act on your email
Accessible Email evaluates your email code and helps make it more accessible for all your readers. You can paste your html or point it towards an online version link.

This tool is mainly used by email marketing professionals and industry campaign developers. It isn’t purely about subject lines, but still very helpful to see if you can improve your metrics. It gives you an overview the level of accessibility and possible improvements.

Validate the HTML of your email, Check for accessibility features, Give advice to improve and build on. And best of all, it is 100% Free.

5. Email subject line grader from Netatlantic

See the impact of characters, emotion and use of words.

The subject line grader from NetAtlantic gives your subject lines a scoring based on the following criteria:

Character & word count No grader that doesn’t count the words and characters. Research will tell us that most effective subject lines have 60 charaters or less.

Type of subject line: Is your subject line classified as “question” a top or a “how-to”? This part also includes tips on how to increase the strength of your subject lines. subject lines.

Word balance: Did you use any action, emotion or power words? Strong subject lines have at least one of those, so be prepared to get that tip and include words that trigger opens, clicks and conversions.

Subject line testing tools, which should you use?

As you’ll have realized by now there is some overlap and differences between what these subject line testing and grading tools measure and score. Some are very basic, others more specifically looking at things like rendering or spammy-ness, while others take a more advanced approach using AI to predict the strength of your subject lines. Our advice give multiple subject line tools a try and see which helps you nail some best practices and more creative at the same time.

About Jordie van Rijn

Jordie van Rijn is an independent email marketing consultant and analyst. He is the founder of Email Vendor Selection and specializes in smart email marketing, online marketing strategy, software selection, campaign management, optimisation and RFP / vendor selection. He tested, reviewed, and wrote about 100+ business software including email marketing services, CRMs, ecommerce platforms, and online course creators. Published in-depth email marketing guides for financial service, ecommerce, travel, restaurant, and fashion industries.
Named one of "50 Online Marketing Influencers to Watch" by Entrepreneur magazine. Companies like Scania, KLM, Unilever, AEGON, CZ, FNV, NRC Media have asked me for advice.

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