Email Subject Line Generator

Free AI-Powered Subject Line Ideas to Drive Open Rates

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Email Subject Line Generator

How to get the most out of generative text.

Don't Settle for Snooze-Worthy Email Subject Lines: Try Our Free AI-Powered Tool and Boost Your Email Open Rates

The world doesn’t need another boring AI-powered tool that generates soulless, subpar subject lines that’ll make you cringe. That’s just silly. That’s why we’ve trained our AI email subject line generator on the most effective email subject lines we’ve used to grow Close for more than a decade. 

A word of warning from one sales pro to another: don’t just drop these AI subject lines into your next email sequence and hit send. Think of our automation tool as a brainstorming buddy. Read the lines it suggests, then add in your own flavor to make them sound more you. Your goal is to write better email subject lines and start real sales conversations—not just blast out the craziest subject lines you can come up with.

Remember, email is all about building relationships, not just optimizing for vanity metrics.  

Here’s a crop of email subject lines generated using our AI tool for a podcast interview outreach campaign. As you can see, it’s a great start, but it still needs a human touch—that’s where you come in.

Once you’ve combined the speed of AI-powered first drafts with your experience, you’ll land on a set of great email subject lines to test in your next email campaign. 

How to Use this AI Email Subject Line Generator to Increase Your Open Rates 

Let's face it, not all of us are born wordsmiths. Trying to write that perfect email subject line isn’t always an easy task. Plus, it eats away at precious time you could spend engaging with potential customers or crafting an effective pitch in the body of your email. 

Good news: Close's GPT-3 powered email subject generator is the ultimate relief to your subject line woes. With the click of a button, you'll receive 10 completely customized subject lines to serve as a starting point for improving your email open rates.

Here's how to wrangle the controls of this free AI-powered tool:

1. Type in Your Email Topic, Desired Tone & Email Subject Length 

Start by giving our free tool some quick info about your email. Are you trying to book more meetings, get guests on your podcast, or follow up on a cold email? How do you want the subject line to look & feel? Let the tool know! 

Start by briefly explaining the goal (subject) of your email and setting your Tone & Length requirements for your subject lines. 

Some detail is helpful here, but no need to go too in-depth. You’ll want to take the subject lines this tool generates and iterate on them yourself, anyway—remember, this tool is designed to give you inspiration. Think through answering these kinds of questions about your email: 

  • Are you connecting with a cold prospect or encouraging a current customer to upgrade to a higher plan?
  • What’s the purpose of your email? What’s the core message you want to communicate?
  • How do your prospects like to be spoken to? Casual, formal or somewhere in-between?

The more information you give the tool, the stronger and more contextually relevant your sales email subject lines will be.

2.  Hit “Generate Email Subject Lines” 

That’s it! We built this tool to be simple and easy to use. Once you click generate, the AI-powered wizardry behind the scenes will generate a list of 10 different subject lines related to your description and the options you’ve toggled. 

Choose the email subject line that fits your email, style, and goals best. Then, tweak it to make it more personal and you're ready to add it to your email campaigns.

3. Test Different Prompts 

Remember, the tool only has one or two lines to go on, so if your first batch of email subject lines doesn’t hit the mark, try a different prompt. You might add more details: 

Or switch up the Tone and Length options for your subject lines, like so: 

Once you find a few you like, you can either hit “copy to clipboard” to copy all of your email subject lines to your clipboard—or you can individually highlight the one(s) you want, copy and take the time to make them your own in your CRM or email inbox. 

Now it’s your turn to get creative. Experiment with weaving in some key phrases you’ve had SEO success with, use these to fuel A/B testing efforts, or spice up a bland outreach campaign. You can even add those clever new subject lines to your CRM, email marketing platform, or update your stale cold email templates

5 Email Subject Line Templates to Optimize Your Next Campaign 

Whether you’re struggling to come up with cold email subject lines or trying to kick off a new newsletter campaign, coming up with subject lines can be a stumbling block. Sometimes a few subject line suggestions can go a long way when getting into the creative flow just isn’t happening. Here are five of our favorite email subject line templates you can use today. 

1. Idea for your [pain point]

This subject line focuses on delivering value to your prospect in the form of an idea that ladders up to a broad goal they’re reaching for. You can also use it for a variety of cold outreach emails for similar prospects in the same industry without having to personalize each one. 


  • Idea for your eCommerce store
  • I have an idea to grow your traffic

2. Fellow [personalization] 

The best cold email subject lines don’t sound like cold emails. This subject line leverages commonalities you have with a prospect. This shows them you’re a real person and have actually taken the time to learn a little bit about. Them. 


  • Fellow UNC grad
  • Hey from a fellow SF native

3. Quick question [optional personalization]

This is one of my all time fav subject lines because its short and simple. (As all good email subject lines should be!) You can also add context like this: 

  • Quick question about your content process 
  • Quick question from Ryan at Close 
  • Quick collab idea from Close 

4. New tool for [type of role/problem]

Connect with a cold lead immediately by mentioning their job role or a problem they face. Personalizing a subject line with a minor tweak like this can help your email get noticed in a prospect's inbox. Plus, keeping it short indicates there’s a good chance your email is short, too. 


  • New tool for busy marketers
  • New tool for getting more leads

5.  Frustrated with [pain point]? 

This subject line is short, to the point, and shows contacts you understand what makes their lives difficult. There’s no need to wax poetic in your subject line – the goal is to get them to open your email. 


  • Frustrated with the new Google update? 
  • Frustrated by a leaky sales funnel? 

How to Write Email Subject Lines that Get Higher Open Rates 

AI writing tools like our email subject line generator, serve as a starting point. Think of these outputs as solid first drafts—or having a creative partner to brainstorm with. Don’t just grab the first email subject line the tool spits out and expect to see a 1000% increase in open rates.

With more than a decade of experience sending sales emails, we’ve learned a bit about nailing your email subject lines. Here are our top tips for email subject lines that actually start conversations with prospects

1. Really Get to Know Your Potential Customers & Prospects

Before crafting email subject lines, take time to really get to know your target audience. Don’t just think about what you want them to do; think about what topics they care about. What pain point keeps them up at night? How does seasonality impact their industry? When you really know who you’re talking to, you can tailor your subject lines to resonate with their needs.

Consider collaboration with other teams, including your support and marketing team to understand what language is likely to resonate with your target audience. Use all this info to create hyper-personalized, relevant subject lines. You can also check out our 61 proven email subject lines for more inspiration. 

2. Keep Your Email Subject Lines Short (Especially for Cold Emails!) 

The subject line is, without a doubt, the most crucial part of any email campaign. Why? Because if it fails to grab your prospects' attention, they won't even bother opening your email, and all your hard work will go down the drain.

So, what's the secret to crafting an irresistible sales email subject line? 

Keep it short and sweet. You could go on and on with a lengthy subject line, but guess what? Email clients will just chop it off. Do yourself a favor and stick to a neat 20 to 40 characters. 

3. Reel Them in With an Intriguing Hook 

Pause for a moment and take a sneak peek into your bustling inbox. Chances are, you'll find a swarm of emails eagerly vying for your attention. Now, imagine this: your subject line is the shiny lure, the irresistible bait that can either entice your prospects to bite or make them swim away.

How do you ensure your hook is irresistible? It's all about standing out from the crowd. Consider leveraging the power of curiosity, posing a thought-provoking question, or teasing them with a tantalizing hint of what awaits in your email.  

Remember, the goal is to build a genuine connection with your prospects from the subject line right through the closing line.  

4. Avoid Spam Words (and Think Hard About Those Emojis) 

The best subject lines are catchy and pique your contact’s interest. But your email subject lines can also land you in the spam box. Most email providers use spam filters and algorithms that send emails with specific words straight to the spam folder. So, how do you avoid the spam box? Avoid using spam words like: 

  • Cash
  • Free 
  • Get paid now 
  • Perfect
  • Unbelievable 
  • 100% Off 
  • Cures 
  • Act Now 

Emojis are another feature that can kill your email marketing campaign before it's even started. One study found emojis increase negative sentiment towards emails and don’t increase open rates. They might make sense for your audience, but take some time to consider whether it's really a good fit before testing. 

5. Inject (a Little) Urgency

Spare us the cliché subject lines like "LAST CHANCE BEFORE THIS AWESOME DEAL IS GONE FOREVER." That's so 2010. Instead, infuse your subject line with genuine urgency. Highlight the benefits they'll miss out on or the amazing results they could achieve with your help.

Consider adding specific deals, numbers, or a time frame that highlights what they’re really missing out on if they don’t open your email. 

6. Get Your Email Copy Right 

Good email subject lines are just the start. Whether you’re sending cold emails or trying to sign ups for a webinar you’re hosting, take the time to craft email content that provides value, addresses customer pain points, or convinces them to hit that ‘reply’ button. The content of your email can make or break a campaign’s success, so don’t leave your audience hanging.

And if you’re not a copywriting expert, consider using our cold email generator to create your entire first draft. Just provide key info about your business and the type of email you want to create, then hit ‘generate.’ 

Who is This Email Subject Line Generator Best For?

We designed this AI subject line generator to craft highly effective subject lines, no matter what your goal is.  So, what are the best use cases for our free tool? Try it out for these types of emails: 

  • Cold emails: Break the ice and warm up those prospects with catchy email subject lines that make prospects want to get to know you better. 
  • Newsletters and product updates: Capture your reader’s attention with subject lines that make your subscribers eagerly dive into your content.
  • Follow-up emails: Revive those stagnant conversations with subject lines so engaging, they’ll be filling your inbox with responses. 
  • Abandoned cart emails: Whether you’re a SaaS company or an eCommerce giant, the right email subject line can send indecisive shoppers rushing back to complete their purchase. 
  • Thank you emails: Show your gratitude in style by using subject lines that bring a smile to your customers' faces and make them feel like VIPs.
  • Introduction emails: Make a memorable first impression with subject lines that ensure your message won’t get lost, even in an overflowing inbox. 
  • Office pranks: Ok, maybe this isn't a typical use case, but I’ve been having fun using this subject line generator to craft silly subject lines to try and top my co-workers with a little light-hearted mischief.

Always consider your audience, brand voice, and the context in which you're using these subject lines. Some may work wonders, others could fall flat. Adopt a mindset of experimentation and continual improvement & you’ll be well on your way to starting more sales conversations.

Remember that at the end of the day, you’re sending a message to a real person on the other end of the line here—take a moment to feel how you’d react to getting this subject line in your inbox. When you’re happy with that feeling, you’re on the right track.

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