Iuliia Nesterenko

Technical Writer

15 Email Subject Line Generators to Boost Your Open Rate

15+ Email Subject Line Generators to Boost Your Open Rate

A subject line is an important element of every email campaign. Together with a sender name, it’s the first thing recipients see in the Inbox. When composed badly, it can also be the last one, so marketers put much effort into cathсy phrases and attention-grabbing expressions.

However, sometimes even the most talented and experienced copywriters get stuck with composing a good email subject line. This is where a random subject generator can help you come up with a couple of smart lines or at least give some inspiration. Most of them are free and easy to use. Just enter the word and choose between the suggested combinations.

Here is the list of 15 free email subject line generators you can start with straight away. Create cool lines that will get your subscribers to pay more attention to your messages.

How to Write Spam-Free and Getting-Opened Email Subjects

Before we proceed with looking for a newsletter titles generator that works best for your email marketing goals, let's take a quick look at effective email subject lines writing practices. The matter is that a newsletter titles generator is actually a powerful tool, but the suggestions provided by it can rarely be used in a "copy-paste" way. Their main goal is to help you unleash your creativity and generate great ideas using the combination of human and machine thinking. Below are the main rules to create a powerful and compelling subject line in an email, regardless of the reliance on a newsletter titles generator.

  • Use powerful words. Choose impactful and attention-grabbing words that evoke emotion or pique curiosity. Using "action" words like "try", "discover", "learn" are also effective for driving a high-open rate.

  • Avoid spam-trigger words. Such words as "free", "cash". "unlimited", "free money", "get rich quick" and so on significantly increase the chances of your letter getting into the spam folder.

  • Keep it short, meaningful, and catchy. A good email subject line shouldn't exceed up to 5 words, while you have to do your best to put all the meaning in them. Aim to keep your subject lines succinct and impactful.

  • Avoid misleading claims. In addition to being one of the best practices for writing effective email subject lines, it is also one of the tips to build trustful relations with your audience. Make sure your subject line, the letter content, and the actual offer match each other accurately.

  • Avoid excessive punctuation. Using excessive exclamation marks, dollar signs, or other special characters can make your subject line look spammy. Stick to minimal punctuation for a professional appearance.

Checklist for Creating Effective Newsletter Subject Lines

  • You have clearly conveyed the purpose or main point of the letter

  • Your subject line is short and concise

  • Your email subjects are relevant to the recipients

  • You have personalized both the letter and its title

  • You have followed your brand tone of voice

  • You have created a FOMO effect (but avoided using spam words)

  • You have no grammar mistakes or typos in your subject line

  • It is attention-grabbing but not sensationalist

1. Mailmunch

Mailmunch subject line generator

Mailmunch is an email marketing platform that has an email subject line generator as one of its features. To get subject line suggestions, you have to specify the main topic of the letter (for example, new products arriving in your store), enter the name of the company, and choose a tone to align your email marketing subject line with your brand voice.

2. Encharge

Encharge subject line generator

Encharge is an email subject line generator of a new generation since it is powered by Chat GPT-3 technology. It works in the same way as the previous solution, however, this tool is more on understanding human psychology and delivering email subject lines that resonate with subscribers.

3. Copy.ai

Copy.ai subject line generator

Copy.ai is an all-in-one copywriting assistant, that also has an email subject line generator, in addition to a tone changer, "Explain like I'm 5" and Facebook headlines generators. This tool takes creating catchy email subject lines seriously. You are welcome to describe the goal of the letter, add the details you would like to share in its content and get the list of ideas. Then, you can ask the tool to create more subject lines of the type you like, save the most winning suggestions for later and adjust subject lines in the ways you like. 

4. Portent

With the Portent email subject line generator, you can type the subject and swipe through the options. Click any word in the title to see why it has been used. Save your ideas or tweet those you find interesting or funny.

Portent subject generator

5. Best Online Title Generator

The most modest subject generator of them all. Enter the keyword, select out of 700 headlines and edit the grammar if needed (which most probably will be the case).

6. WebX

This is a blog post idea generator, but feel free to use it for your email titles as well. The useful functionality the platform has is idea googling. Choose the option you like, click Google this idea and see what Google has on this topic.

7. ActiveCampaign

ActiveCampaign platform has long been known for its outstanding marketing functionality, with an email subject line generator in-built. Choose a keyword category (Benefit, Topic, Pain Point) and enter your keyword. You can see 4 suggested subjects at a time. To see new combinations, click Generate more suggestions.

ActiveCampaign subject generator

8. Cold email subject line generator

Cold email subject line generator is a free tool by Reply that works similarly to ActiveCampaign. Choose one of 4 categories (Benefit, Problem, Personalized, COVID-19) and enter the keyword. Generate more suggestions if you can’t find the right one. All lines displayed in the window can be exported as an excel file.

All tools for marketing automation within one platform

9. Outtale

What makes the Outtale email subject line generator different from previous solutions is that with it,  you can’t search by keywords. Instead, select the style and idea and see the possible combinations. Titles are copied in one click that’s rather convenient.

10. Hubspot

Perhaps, Hubspot needs no introduction. Being an all-in-one marketing automation solution, it has many email marketing tools as well, including an email subject line generator. Enter up to 5 nouns to get 5 ideas for blog posts. Register to unlock 250 ideas that are promised to provide you for a year.

Hubspot subject generator

11. SEOPressor

This blog title generator can give you ideas on best subject lines for email marketing as well. Enter your keyword and select the category it’s more likely to belong to. It can be a generic term, event, location, etc. The tool shows 10 results at a time, but the suggestions are numerous. I entered email as a generic term and got 1,160+ titles. Many require optimization, you’ll get ideas to work on.

12. Mizy

Mizy is an AI-powered subject generator that offers you suggestions based on the copy of your email. It’s still available in the beta version but already can give you some nice lines. So, if you are looking for an email subject line generator of a new generation, give it a try. 

Look at the copy and original subject line, and then at the option the program gave me. Not perfect, but you may get a better result with more text available.

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Subjects by Mizy

13. Headline and Subject Line Generator by Google

This is an extension you can use straight in your Gmail account. Google-created email subject line generator can give you a hand when you send bulk emails with Gmail, write a corporate newsletter or want to get fancy when writing to your friends.

Choose between four categories – List, How To, Question, General – and enter the keyword or phrase. Gmail offers rather standard versions, but they’re all good and grammatically verified.

Subject by Google

What’s more, you can switch from Swipes to Headlines (top right corner). This tab also has four categories – Email Series, Promos, Blogging, E-commerce – but offers just general suggestions: you can’t enter your words here.

Last post

14. Tweak Your Biz

This email subject line generator has extra filter options in addition to regular key searching. Enter the word, specify if it’s a noun or verb and choose how you want your results to appear. Suggested options will be formed in categories, and they may differ depending on what you’re looking for.

I entered email and the results were grouped in the categories Lists, Questions, How to, Business, Celebrities, etc. However, the word vegetables generated other groups like Lists, Best, Love, Secrets.


Just your regular random subject line generator. Enter the word to see 10 suggestions. To see more, you need to register.

16. Kickass Headline Generator

An email subject generator by Sumo. It differs from the above platforms in that it doesn’t generate ready suggestions. Instead, it gives formulas based on the conditions you set. You can choose the title format and then specify extra requirements like topic, audience, outcome, etc. So, this is a little unusual email subject line generator that fosters creativity and promotes independent thinking. 

Kickass line generator

17. Content Row

This isn’t just a subject line creator but an entire content management tool. In addition to headline generation, you can use a headline analyzer, word counter, case converter, etc. A big disadvantage of the platform, though, is its limited usage. Free users are only allowed three headline generator searches per day. Unlimited usage requires a subscription to a PRO pricing plan.

18. Tools.FromDev

A title maker is only one of the services this platform offers to online developers. Go to SEO > Title Maker, enter the subject and check the results. The good thing that the tool can generate some good suggestions; the bad thing is that they aren’t displayed in a list. You need to keep on clicking Suggest Title to see every next combination.

The above platforms can really be helpful when it comes to creating subject lines. However, they only show you the direction to move in. The editing and final touches are always up to you. Don’t forget about grammar, spelling, SEO optimization, and relevance because even the best generator doesn’t know your audience and their likes.

Also, keep in mind that an email subject line generator gives you only text suggestions and rare numbers. Feel free to mix them with emojis, symbols and more specific digits.

And for a better marketing result, run regular A/B testing to determine which titles generate more clicks. In our service, you can test email subject lines in two methods: within one email and with several emails sent to different segments.

The results are displayed in the campaign report in a separate tab. The winner option is highlighter green, and you can see what percentage advantage it had over competitors. Such tests help adjust marketing strategies and often may be the answer to the question “How to get my emails opened?”

Subject A/B test report in our service

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Iuliia Nesterenko

Technical Writer

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