Best email subject line generators

A good email subject line can make a difference when getting more leads and customers. Remember that you only have one chance to make an excellent first impression.

Suppose you are a business owner, a freelancer, or a person looking for a job. In that case, you need to be confident that your recipient will be interested in opening your email. Since it is the first sentence recipients read in their inbox, a great line will give you more chances to catch the recipient’s attention and open your email.

A subject line generator is a tool that helps you validate the whole aspect of your email subject.

According to Omnisend, one of the biggest companies in the email business:

35% of customers open emails based solely on the subject line.

69% of customers mark an email as spam based on the subject line.

59% of customers say marketing emails influence their purchase decisions.

Today, we all receive hundreds of emails, and most of them go directly to the spam or trash folders.

But sometimes, you can get stuck writing a good email subject line. A subject line generator can help with some inspiration and catchy lines to get your recipient interested in your message.

Remember that a good open rate is only the beginning. You need to get more sales through an intelligent email campaign setting.

So let’s check some applications to help increase your open rate and sales.


email subject line generator omnisend


Omnisend email subject line tester is an excellent free tool for writing a good email. It gives you a score based on character length, word count, helpful words, negative words, and scannability.

Suppose you are out of ideas and suffering from some writer’s block. In that case, Omnisend can show suggestions for better words and readability.


RELATED: 15 Best Email Finder Tools




Subjectline is a free subject line rating tool. This site will evaluate and rate your email subject line from zero to 100, so you can check it and modify it to get a high score. It also gives advice on which part of the sentence you should change (Capital letters, sense of urgency, length) to get a great subject line.


Active Campaign


This free email subject line generator provides lines based on specific keywords. You can choose among three keyword categories (Benefit, topic, or pain point) and then the app will show suggested subject lines.


The readability checker


The Readability Checker scores your writing based on the Flesch reading ease scale, which looks at how long your words and sentences are. Since it is based on the Flesch scale, you can adjust your tone depending on the audience you need to reach.

This is a free tool, and you only need to register for a free account to test your emails.

Test Subject by Zurb

email subject line generator testsubject


TestSubject by Zurb is an online tool to test your email subject and how it will show on mobile devices. Since mobile email clients and devices tend to shrink these fields, it is good to see how your line will look.

This is an excellent tool to test your subject line on most popular devices and email clients, view how your sender name displays and your pre-header text.

Considering that about 50% of emails are opened on mobile devices, this tool is a must-have.



This site provides an excellent tool to analyze your email and write a better copy.

Mailshake claims that the two biggest killers of a cold email campaign are emails that get caught by spam filters and emails that are hard to read.


RELATED: 10 Best Email List Management Software




CoSchedule email subject line analyzer is a free tool to tune your copy and avoid spam filters with catchy text and the right headlines. You have to register for a free account. Coschedule will help write subject lines with the correct words (“free” is a word that probably drives your email to the spam folder), tone suggestions, character, word count, numbers, and emojis.



With Salesblink free tool, you can get great email subject lines with only two clicks. You only have to fill in the service you provide

and the recipient’s company name. Click the “Generate” button, and voila. You get five subject lines with their respective open rates that make people open your emails.

You can repeat the process as many times as you wish, but in my own experience with only a pair of tests I got good results.


Copywriting course


This website has a blank box where you have to enter your topic and then show a list of preset subject lines based on that topic for free.

A basic and straightforward idea interesting enough to try and see which is the best for your email and your audience




email subject line generator portent

Portent is one of the best free tools for generating catchy subject lines. You type the subject and the software will deliver a cre

ative title, and clicking on each word reveals why the word is there.

Click on “see another title,” and you get lots of ideas, pick the one you consider interesting for your audience, and craft your email.


Kickass Headline Generator


This free tool has a different approach. You set conditions such as about, numbered lists, how-to, explanatory, strong/controversial, fun/playful, and DIY headline formulas. Then you get formulas based on the conditions you set.



Mailmentor is a free platform to paste your message and get recommendations about improvements, language options, and pa

ragraph length. It also gives reading time and reading grade level, a key metric to reach specific audiences.




Fatjoe is a blog post title headline generator, but it works fine when you need a good subject line idea for your email.

You type your central word, and the system generates ten suggestions that you can tweak. You need to register to get more than ten ideas.


Send Check It

email subject line generator

Send Check It is one of the best email subject line generators, but consider registering to use this tool. Then you can paste your copy and get scores about scannability (a measure of how easy-breezy it is to read your subject line), reading grade level ( a mixture of word choice, complexity, and length), sentiment, personalization, and spammy words.


Email subject line from Netatantic


This free email subject line tester gives a general score based on:

Character and word count; (best subject lines have less than 60 characters)

Word mixture and balance; (count if you use action or emotional words for better subject lines and open rates).

Type of subject line; (are you using “questions” or “how to” lines)



email subject line generator


ISnotSPAM is a free tool that goes one step beyond subject line testing. You send your email, and the app analyzes the subject line and the body message to avoid spam filters. You can see an online report reporting potential problems (if any) with your email.

The test is based on SPF, Sender-ID, DomainKeys, DKIM, and spam Assasin checks.

Although sending your complete email to their website may represent a privacy concern, it is a comprehensive tool to avoid landing on the wrong folder.

email subject line generator is an AI-powered tool that helps you create human-like emails focusing on personalization. This assistant is powered by an AI-backed algorithm that creates better emails and maximizes open and reply rates.

An excellent email quality checker that scores your email and gives feedback about how likely it will be to receive a response based on subject line length, word count, reading level, and other parameters.



All of these tools have a different approach to score your subject line. From the elementary ones to those using AI prediction, all share a common objective; to make your email interesting enough for the recipient and to increase your email open rates.

Test them and see which helps you better to reach your goals.

And if you are using a tool not listed here, please leave a comment and let us know.

Happy emailing!


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