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25 January

10 Best Free Subject Line Generators to Boost Your Open Rates

Stripo / Blog / 10 Best Free Subject Line Generators to Boost Your Open Rates

Subject lines can make or ruin your email marketing campaigns. If your emails don’t get opened, the hours you spent on creating the campaign, writing the copy, and setting up the automation won't be worth it.

About 47% (almost half of your email recipients) open an email if the subject line catches their attention. While a whopping 69% of recipients report emails as spam just by looking at the subject line. 

So yes, subject lines are kind of a big deal.

Like most email marketers, we struggled with coming up with a fresh, interesting, and concise copy on most days. We’ve all been there. 

Good news! There are subject line generators that can come to our rescue. These tools help you write subject lines fast. Not only that, they produce unique and relevant copy every time you need them in just seconds. 

We've collected some of our top picks here in this post, and we hope they will be helpful to you. But before that, let’s define a subject line generator.

What are subject line generators?

A subject line generator is a service that helps you generate an email subject line for your company. They offer multiple options for a custom subject line based on the content of your email. 

If you're an email marketer, you deal with a lot of things on a day-to-day basis. Coming up with a line of text sounds simple and fast. But at one point we’re just too busy, tired, or rusty in coming up with ideas for subject lines. 

That's where subject line generators come in handy. Check out some of the best ones that will ignite some inspiration.

10 Best Free Email Subject Line Generators

1. Encharge

Not into all those generic subject line generators? Encharge gets it. That’s why they created a unique and only free AI email subject line generator based on the GPT-3 technology. Meaning, it will crawl the Internet and generate copy by using words that humans will normally use.

AI-Powered Subject Lines Generator

Simply enter the topic of your email, your company, and your preferred tone. Hit generate and the tool will produce 7 compelling subject lines for you. Keep hitting the generate button until you see your preferred output. 

2. Keap 

Keap’s free email subject line generator promises to produce subject line ideas that will get sales and marketing messages opened. 

Best Free Email Subject Lines Generators

Using it is simple. First, choose the type of email you're sending from their list. Second, specify your keyword and the audience, and the pains they're trying to avoid. 

Just like that, you'll get five subject lines that you can use to get maximum responses. You can choose the tool to generate more suggestions.

3. ActiveCampaign

If you’re more into a specific keyword, ActiveCampaign is the free email subject line generator suitable for you. You get email titles using your keyword and its category (Pain Point, Benefit, or Topic). 

Free Email Subject Line Generators

Four suggestions are displayed at once. Select ‘Generate more suggestions’ if you wish to see more options.

4. Jarvis

Jarvis is an AI copywriting assistant. The tool is actually paid software, but if you contact its support they offer a 5-day free trial. During this period, you can try out how the tool helps produce various content including blog intros, video titles, and email subject lines. 

Best Subject Lines Generators for Your Email Campaigns

In its input fields, you can set your product or company name, tone, and what your message is about. Also, you can set the number of outputs you want.

5. is an online tool for generating content ideas. You can select a generator for blogs, ads, and social captions and use the idea as your email subject line as well. 

Subject Line Generator_Best Free Tools

Enter the topic of your email and a description of your product, service, or company for it to run content suggestions. 


A straightforward free email subject line generator. is easy to use, with just 2 inputs needed from its user. 

Generators of Subject Lines for Email Marketing

Write who the email is from or what the business or product does, first. Afterward, input the intent of the email and you will get 5 copies. Click ‘Create Copy’ again to refresh with 5 new suggestions.

7. Funnelfly

This free email subject line generator is different because it delivers the email subject lines suggestions to you via email. Funnelfly gives a list of custom subject lines straight to your inbox.  

Email Subject Line Generator_Free

The information it collects includes your email address, keyword/topic, your name, and your company.

8. Copymatic

Copymatic is a tool that offers to generate copy in seconds — whether it's for social media, ads, landing pages, emails, or blog posts. They give out 10 credits for a free trial so you can explore the entire generator.

Free Email Subject Line Generators for Boosting OR

Its free email subject line generator is easy to use too. Simply explain with as many details as possible to the AI what you would like to write about by filling in their form. Input the tone of your message, product name, and description, and even adjust the level of creativity of your AI helper.


Rebranded as SalesBlink, this free tool is for creating cold email subject lines. 

Free Subject Line Generators for Powerful Email Marketing Campaign

By inputting the service you provide and the recipient company name, you’ll generate subject lines with corresponding predicted open rates. You can click “Generate more” so it shows fresh 5 new title inspirations.

10. Portent

Portent idea generator is the simplest of them all. The only input needed from the user is the subject of your message. 

Tools for Generating Subject Lines

It is not specifically targeted for email subject lines but you can get inspiration from its recommendations. Click “See another title” so it gives you a new one ― one at a time. 

5 quick tips for writing sticky email subject lines

The subject line of an email is powerful. It's important to remember that your subject line should be intriguing to get someone to open your email, but not so lengthy as to be overwhelming.

Here are a few tips to do it:

1. Keep it short

The best way to write an effective email subject line is by keeping it short and sweet. Use a few words that describe what you're sending and why someone should open it up. 

2. Treat it like a shorter headline, or get straight to the point

In your posts, headlines affect whether the audience will proceed reading them or not. Likewise in emails, subject lines can influence if recipients will open them, ignore them or worse, move it to junk and mark it as spam. So, your subject should make it clear what the email is all about just like how you craft your headline to draw attention.

Stripo's experience showed that concise subject lines where you get straight to the point increase email opens by 200%.

3. Put a kick on it

Adding a sense of urgency to your subject lines is one way you can get people reading. Trigger them with an immediate call-to-action in order for it to be compelling enough. 

4. Personalize your message

Experian's research report showed that personalized subject lines like subscribers' names boosted opens by 26%. However, personalization goes beyond “HI NAME” these days. Personalization means your message connects with readers via the topic itself, timing, and intent.

5. Test, test, test

To ensure the effectiveness of your email marketing campaign is by split testing different subject lines. This way, you see which ones work better than others for capturing more open rates. The key here is understanding what your audience likes because if you know them well enough then your emails will reflect their interests. 

In our "100+ subject lines to boost your OR" blog post, we've compiled over 150 email subject lines for your inspiration.

18 min read

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100+ Best Email Subject Lines to Boost Open Rate Read

Wrap up

Subject lines can help you create interest in the email. But once in a while, even the pros struggle to write them. So if you’re having difficulty coming up with an attention-grabbing headline or subject line for your email campaigns, take advantage of the free subject line generators and see how fast you can work through your emails.

Subject line generators make it easy to create attention-grabbing headlines without spending more time thinking (reserve it for strategy-heavy work). 

Speed up email production with Stripo

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