5 FREE Subject Line Testers for Your Email Marketing Strategy

Email Subject Line Testers_Pretty Links

Sending emails is one of the easiest ways to reach your audience. In fact, this strategy has proven to be more effective than social media ads for promoting products and services. However, if your subject lines are not interesting enough, your email marketing efforts may be going to waste. 

Fortunately, there are several tools that can help you create impactful subject lines for your emails. Moreover, these headline testers can give you recommendations to help reduce the likelihood of your content being ignored or ending up in the spam folder.

In this post, we’ll take a closer look at subject line testers and why you should consider using them. Then, we'll recommend five powerful tools that can help you increase your email open rate. Let’s get started!

Why You Might Want to Use a Subject Line Tester for Your Emails

A recent study shows that 44% of people in the US and Canada check their email inboxes about one to three times a day. In another survey, 48% of respondents said they are happy to provide their email addresses to companies to receive discounts and offers.

Therefore, email marketing enables you to reach many people who may already be interested in your brand. This opportunity can help you increase your return on investment (ROI). For instance, you could send emails to promote your affiliate products, using our Pretty Links plugin to create branded links and track conversions. 

However, given that many people receive several promotional emails per day, your own messages may go unnoticed:

The use of subject line testers can help your promotional emails stand out in a Gmail inbox

This is where subject line testers come in. These tools help you create subject lines that can make your emails stand out in a busy inbox. All you have to do is enter a title for your email and the program will give you recommendations for improvement. 

Using subject line testers can be an effective way to create emails that convert. For instance, you can follow a set of suggestions to make calls to action (CTAs). These can prompt users to open your email and complete an action, such as “Take our survey for a chance to win $50!”

Some tools also enable you to see what your subject line would look like on different devices. This will help you ensure that the text is fully visible on different screens. Having easily viewable subject lines can increase the likelihood of your emails getting noticed and opened. 

5 Best Subject Line Testers for Your Email Marketing Strategy

Let’s look at five powerful subject line testers that can help you increase your open rate and drive higher conversions. 

1. Email Subject Line Tester by CoSchedule

CoSchedule offers a variety of marketing tools to help businesses succeed, including an email subject line tester:

Email Subject Line Tester by CoSchedule

Once you enter your subject line, you’ll get a score and a list of suggestions:

An overview of your subject line in Email Subject Line Tester by CoSchedule

For instance, CoSchedule recommends that you use title case, numbers, and emojis in your subject line. These elements are likely to encourage users to open your email. You’ll also get a list of words that help you perform better, as well as ones that you should avoid. 

2. TestSubject by Zurb

Around half of marketing emails are opened on mobile devices. Thus, it’s important that your subject lines are also impactful on smaller screens. 

TestSubject by Zurb enables you to check your content on different mobile devices:

TestSubject by Zurb

You can start by entering the sender name and subject line. You also have the option to add pre-header text. Then, Zurb will show you what this information will look like on mobile phones:

An example of an email subject line on a mobile device.

There are currently three options available: iPhone 6, iPhone 6 Plus, and Samsung Galaxy Note 5. Since most of your audience will be accessing their inboxes on mobile devices, we recommend that you use short and snappy subject lines in your email campaigns

3. Refine by Moosend

Another powerful subject line tester is Refine by Moosend. This tool will first ask you to select your niche and number of subscribers, followed by your subject line:

Refine by Moosend

Refine will then use this information to predict your open rate relative to your industry's average: 

A prediction of your open rate in Refine by Moosend

It will also give you some suggestions to improve your performance. For example, adding a question mark might make you sound friendlier and more approachable. This tool also recommends that you segment your audience and write subject lines that target specific groups. 

4. Email Subject Line Tester by Send Check It

If you’re looking for a tool that provides a more in-depth analysis of your subject line, check out Email Subject Line Tester by Send Check It:

Email Subject Line Tester by Send Check It

This tester evaluates different aspects of your content, including its scannability, length, and reading grade level:

 Send Check It evaluates the scannability and reading grade level of your subject line

It also highlights any problematic elements in your subject line, such as exclamation marks and spammy words. Moreover, it shows how you can personalize your content to make it more engaging and encourage opens. 

5. Subject Line Tester by Omnisend

Omnisend is an omnichannel marketing platform for ecommerce businesses. Its subject line tester offers valuable insights that can help increase the visibility of your emails:

Subject Line Tester by Omnisend

After submitting your subject line, you’ll see how your content fares in terms of scannability, length, and wording. It also shows you specific examples of helpful and negative words:

Omnisend checks the wording of your subject line.

For instance, the tool will point out any word that could potentially decrease your open rate. It also flags up spammy words and characters in your subject line. Furthermore, it advises you on capitalization, punctuation, and the use of numbers. 


Emails with attention-grabbing subject lines can help you boost your open rate and drive more conversions. Using a tool that analyzes your headlines can optimize your content and increase its chances of being noticed. 

In this post, we looked at five subject line testers that can help you maximize your email marketing strategy:

  1. Email Subject Line Tester by CoSchedule: This tool analyzes your subject line and provides a list of words that could increase your open rate or discourage clicks. 
  2. TestSubject by Zurb: You can use this tool to test how your subject line will appear on different mobile devices. 
  3. Refine by Moosend: A subject line tester that gives you open rate predictions and suggestions, based on your industry and number of subscribers. 
  4. Email Subject Line Tester by Send Check It: This tool evaluates your subject lines on several factors, including length, reading grade level, and scannability. 
  5. Subject Line Tester by Omnisend: It checks your subject line for spammy elements and gives recommendations for words that could generate more clicks. 

Do you have any questions about using subject line testers? Let us know in the comments section below!

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Categories: Marketing Advice
About John Hughes

John is a blogging addict, WordPress fanatic, and staff writer.