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11 Best Subject Line Tester Tools

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Published on
October 11, 2022

Do you need someone to test your subject line? You're safe with us. We've compiled a list of 11 tools to assist you in creating flawless email subject lines.

We'll go through 11 free and paid subject line tests in this blog article to help you get better results. We'll cover everything from tools that assess the emotional impact of words on users to those that may help you determine the ideal mobile-friendly subject line length and avoid spam filters.


Increase Email Open Rates with These 11 Subject Line Tester Tools

Do you need someone to test your subject line? You're safe with us. It's not easy to come up with the ideal email subject line. To acquire the greatest possible open rates, you need to strike a balance between inventiveness and expertise of your target audience. While this may appear to be a difficult task, topic line testers are available to help. These gadgets make the procedure go more smoothly.

11 Best Subject Line Tester Tools

While some imagination is still required when writing subject lines, technology has made it easy to use data. You'll discover a variety of tools in the list below, each with its own set of features and usefulness. Some are more advanced than others, but even the simplest tools offer a distinct viewpoint that can aid in the production of outcomes.

Increase Email Open Rates with These 11 Subject Line Tester Tools

11 Tools to Improve Open Rates: Subject Line Testers

1. Mizy by Automizy

2. Test Subject by Zurb

3. Email Subject Line Grader by Net Atlantic

4. Send Check It

5. Spam Check by Postmark

6. Touchstone

7. SubjectLine.com

8. ISnotSPAM

9. Emotional Marketing Value Headline Analyzer by The Advanced Marketing Institute

10. Subject Line Tester from Moosend

11. Email Subject Line Tester by CoSchedule

1. Automizy's Mizy

Make better topic lines using AI and Deep Learning. Free of charge

Mizy claims to have a unique perspective on topic lines. Mizy combines AI and deep learning to help you identify the perfect email subject line, unlike other subject line testers. Mizy also has access to a database of emails and is aware of their open and click-through rates.

Mizy's deep learning neural network makes this possible. It can gather data and reorganize itself to deliver more useful insights into what works and what doesn't in order to improve email outcomes. Mizy will provide a performance rating (out of 100) and provide advice on how to enhance your text once you've supplied your subject line.

2. Test subject by Zurb 

Make email subject lines that are mobile friendly. Cost: nothing 

Email subject lines on mobile devices are frequently abbreviated, which most consumers are unaware of. What was the end result? Long, nearly painful-to-read subject lines Zurb became aware of the situation and took action. Test Subject was created by their product design team to guarantee that email subject lines on mobile acquire the attention they require to deliver outcomes.

It was an excellent decision. Smartphones account for more than 57 percent of all internet traffic in the United States, and researchers predict that by 2023, the number of emails sent by companies and individuals will reach 347 billion. Having the ability to improve email subject lines for mobile will result in smarter, more attractive, and successful emails.

Also Read: Benefits Of Using A Sales Automation Software To Close More Deals

3. Net Atlantic's Email Subject Line Grader

Character count, passion, and power words all have an influence. Price: The Free Email Subject Line Grader assigns a grade based on four factors. These are they:

Type of subject line

The sort of subject line you've made is classified. (Think about subject lines like "how-to" or "question"). Users are also given advice on how to improve their topic lines.

Number of characters

The total number of characters. According to research, email subject lines with 60 characters or fewer are the most successful. The tool will tell you how lengthy your subject line is and will also provide suggestions based on the length of your subject line.

Count the words
The total amount of words. Find out how many words are needed to hold the interest of the reader.

Words like balance and mixture

The number of action, passion, and power words employed in a sentence. If one of these is missing from your subject line, the program will suggest adding a handful to enhance your text.

Net Atlantic's Email Subject Line Grader

4. Send check It

To grade the quality of your text, use 16 criteria.

Send Check for Free One of the more comprehensive topic line tests. It provides an overall score as well as a list of 16 criteria against which subject lines are judged, as well as advice on how to improve your subject line. And the criterion list is quite useful. It checks for spam, punctuation, and whether or not you used emojis.

The following is a list of all 16 criteria:


Length of Grade Level Reading (characters and word)


Sentiment (positive or negative words used)

If the term "free" is used

Spammy words

Bad Tab Phrases

Whether you use all caps words if an exclamation mark appears

Whether or not punctuation is used

Individualization (name, industry, title, interest, or geographic info.)

If the subject line of your email contains a question,

Using all lowercase words or not

Whether or whether your topic line contains emojis

5. Spam Check by Postmark

Incoming and outgoing email spam scores are calculated. Free spam filters are ruthless. They may devastate email marketing initiatives, making favorable outcomes more difficult to achieve. However, Postmark allows you to bypass spam filters. You may enter the whole text of your email (including the subject line) into Spam Check's tool. After that, it examines the contents and assigns a spam score.

Because different suppliers give different interpretations, spam ratings might be difficult to comprehend. Spam Assasin is used by Postmark. For a discussion of how to evaluate your score and subsequently improve it, go to this post.

6. Touchstone

Compare your subject line against 21 billion emails in a database. Essential is $69, Expert is $99, and Enterprise is $297.

Touchstone is a platform for virtual topic line testing. You may test subject lines against a database of more than 21 billion emails. The percentages represent how well your subject line would perform in comparison to comparable subject lines for similar emails in your sector. You may also test up to ten subject lines at once, allowing you to locate the ideal version as quickly as possible.


7. SubjectLine.com

To discover the optimal version, compare your subject line to 800 different guidelines. Free of charge

SubjectLine.com has one of the more comprehensive topic line screening tests. According to the website, the tool tests and evaluates filtering and deliverability concerns using over 800 distinct criteria. In other words, your results are calibrated to be a good predictor of how well your content will do. The results display a score as well as where your topic line is losing points. You'll also get some copywriting guidance in the form of a brief blurb.

8. ISnotSPAM 

Overcome spam filters.

Free of charge

Are you concerned that spam filters will mark our emails as spam? Attempt ISnotSPAM. It's commonly used to test the contents of emails, but it may also be used to test subject lines. It conducts five tests, including:

SPF Check the sender's ID

DomainKeys Verification

Check DKIM

Check with SpamAssassin

To begin, go to the tool's website and copy the one-of-a-kind email address supplied. Use the email address and send your subject line to it by pasting it into the email body (leave). Then, to see the findings, click the "View Your Report" option.

Please keep in mind that results may take up to three minutes to show.

Also Read: B2B Outreach Techniques That Helped Us Win the First 10 Customers

9. The Value of Emotional Marketing The Advanced Marketing Institute's headline analyzer

To build more captivating subject lines, determine the Emotional Marketing Value (EMV) of terms. Free

Emotional Marketing Value is a metric that assesses how a set of words provokes an emotional response. While that may seem impossible to believe, it is based on government study conducted by Dr. Hakim Chishti in the 1960s and 1970s. While this tool is intended for headlines, it may also be used for email subject lines, which are essentially email headlines. They're both meant to encourage your reader to keep reading. The Emotional Marketing Value Headline Analyzer will give your text an overall score. It also specifies the kind the target audience for your copy.

10. Moosend Subject Line Tester

Use artificial intelligence to assess the quality of your topic line and compare it to industry standards. Free of charge.

Moosend's subject line tester, like Mizy's, leverages AI to do real-time analysis. Your results are compared to others in your industry, giving you an idea of how well your subject line would do. The tool also includes suggestions for increasing your open rate.

11. CoSchedule's Email Subject Line Tester

While CoSchedule is most recognized for its content marketing tools, their email subject line testing tool is one of the most useful currently accessible. It's intended to assist marketers in crafting more personable subject lines that convert better. It accomplishes this by assigning a grade to your copy.

Get comments on the best case for topic lines. Numbers. If any numbers have been included. Make sure you have enough characters. Character count It's important to keep track of your words. The word count. Count the emojis. What is the total number of emojis used? A look at how things will look. View a mockup of your topic line on desktop and mobile.


While some subject line tools provide a lot of information, it's always a good idea to try a few. Not all tools are made equal, as you can see. As a result, combine them. Mobile-friendly views, spam filter immunity, emotional marketing value, character length, and more are all things to consider. These tools will work together to help you reach the sweet spot where creativity meets analytics and technology in order to increase email open rates.

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