In the world of digital marketing, assumptions are expensive.
You might think your audience prefers a playful subject line over a straightforward one. You might assume that a bright red CTA button converts better than a green one. But until you have data to back it up, you’re essentially gambling with your ROI.
This is where A/B testing (also known as split testing) becomes the most critical feature in your email marketing arsenal. It allows you to send two variations of an email to a small percentage of your audience, see which one performs better, and automatically send the winning version to the rest.
However, not all email marketing platforms are created equal. While many claim to offer “testing,” the depth, flexibility, and analytical power vary wildly.
If you are looking for email marketing software that offers robust A/B testing features, you don’t need to look to obscure, enterprise-level software. The best solutions are likely platforms you’ve already heard of—but you need to know which ones allow you to test beyond just the subject line.
Here is your guide to finding the best email marketing software with A/B testing features, categorized by what they test best.
The Non-Negotiable: What to Look for in A/B Testing Software
Before we dive into the vendors, let’s establish what separates a “good” A/B testing tool from a “useless” one.
Many entry-level tools offer “A/B testing,” but they often limit you to testing just the subject line. While that is a start, true optimization requires testing the following:
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Send Times: Does the software offer “time optimization” or allow you to test which day/time yields the best open rates?
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Content: Can you test entirely different layouts, copy lengths, or offers?
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Sender Names: Sometimes changing the “From” name (e.g.,
[Company Name]vs.[Founder Name]) has a bigger impact than the subject line. -
Statistical Significance: Does the tool automatically declare a winner based on confidence intervals, or does it just pick the one with the most opens after 4 hours?
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Automation Testing: Can you test workflows? For example, does “Email A” in a welcome series lead to more sales than “Email B”?
With that criteria in mind, here are the top platforms where you can find these features.
1. Omnisend: The Best for E-commerce Testing
If you run an online store, Omnisend is arguably the best platform for A/B testing. Built specifically for e-commerce, Omnisend understands that testing for e-commerce isn’t just about open rates; it’s about revenue per recipient.
Where to find it:
Omnisend is a standalone email and SMS marketing platform designed to integrate deeply with Shopify, BigCommerce, and WooCommerce.
Testing Capabilities:
Omnisend offers a “Product Picker” and automation workflows that allow for incredibly nuanced testing. You can A/B test:
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Newsletters: Test subject lines, content, and send times.
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Automated Workflows: This is where Omnisend shines. You can split test abandoned cart emails or welcome series. For example, you can test whether offering a 10% discount in the first abandoned cart email versus offering free shipping yields a higher conversion rate.
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SMS vs. Email: Omnisend allows you to test the channel itself. You can see if your audience prefers a text message alert or an email blast for the same campaign.
Why it’s a winner:
Omnisend automatically calculates statistical significance and uses a “Winning Algorithm” to send the winning variation to the rest of your list. Crucially, for e-commerce, it tracks the revenue generated per variation, not just the open rate. A variation might have a lower open rate but a 3x higher purchase value—Omnisend helps you spot that.
2. Mailchimp: The Classic Choice for Standard Testing
Mailchimp is often the first name that comes to mind for email marketing. While it has faced criticism over the years for pricing changes, its A/B testing infrastructure remains one of the most user-friendly for small to medium businesses.
Where to find it:
Access A/B testing in the “Classic Automation” builder or within regular campaign creation. (Note: Some of the newer “Customer Journey” builders have different testing limits, so you usually want to stick with the classic campaigns for split testing).
Testing Capabilities:
Mailchimp allows you to test up to three variations (A/B/C) at once. You can test:
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Subject Lines: The standard.
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From Name: Test if your audience engages more with a personal name vs. a brand name.
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Content: Mailchimp allows for full-content split tests, letting you send two completely different email designs to see which layout keeps readers engaged longer.
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Send Times: Mailchimp has a “Timewarp” feature and classic send-time testing to optimize for when your subscribers are most active.
Why it’s a winner:
Mailchimp’s reporting interface is intuitive. It clearly shows you the “Confidence Level” (how sure you can be that the winner actually outperformed the loser). For beginners, it holds your hand through the process, asking you what metric you want to optimize for (opens or clicks) before setting the test duration.
3. Klaviyo: The Data-Driven Powerhouse
If you are a serious e-commerce brand or a SaaS company, Klaviyo is the gold standard. Klaviyo’s entire platform is built on data segmentation and analytics, so naturally, its A/B testing features are among the most advanced on the market.
Where to find it:
Klaviyo integrates A/B testing into both Campaigns (one-off blasts) and Flows (automations). It is available on most paid plans.
Testing Capabilities:
Klaviyo offers “Multivariate Testing” (testing more than two variables) within campaigns. You can test:
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Subject Line & Preheader: Testing the combination of these two is critical because they appear together in the inbox.
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Email Content: Klaviyo allows for “Split Traffic” in flows. You can set up a flow where 50% of people go down Path A (receiving a discount code) and 50% go down Path B (receiving free shipping), then measure the long-term revenue impact over 30 days.
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Intelligent Send Time: Klaviyo analyzes each individual subscriber’s historical engagement data to determine the optimal send time for them—a sophisticated form of testing.
Why it’s a winner:
Klaviyo’s reporting is unmatched. It doesn’t just tell you which email got more clicks; it ties the results back to lifetime value (LTV) . You can see which variation resulted in customers who purchased again 60 days later. If you are looking for software that allows you to test sophisticated automation flows against each other, Klaviyo is the answer.
4. Constant Contact: The Best for Local Businesses & Non-Profits
Not every business needs complex e-commerce metrics. For local businesses, restaurants, churches, and non-profits, Constant Contact offers a straightforward, reliable A/B testing feature that is easy to set up without a steep learning curve.
Where to find it:
Constant Contact’s A/B testing is located in the standard campaign builder under “Split Testing.”
Testing Capabilities:
Constant Contact focuses on simplicity. You can test:
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Subject Lines: Up to 5 variations.
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Send Times: Determine if your audience checks emails in the morning or evening.
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From Names: A simple but effective test for organizations where the executive director or owner might have more sway than the generic “info@” address.
Why it’s a winner:
Constant Contact includes a dedicated “A/B Testing” coach within the platform that helps you set up your first test correctly. It also offers excellent phone support. If you get stuck trying to figure out why your test failed, you can call a human and have them walk you through the analytics. For organizations with limited marketing staff, this support structure is invaluable.
5. ActiveCampaign: The Best for Complex Automation Testing
ActiveCampaign is a customer experience automation (CXA) platform. It combines email marketing, marketing automation, and CRM. Its A/B testing capabilities are geared toward marketers who want to optimize complex, multi-step sales funnels.
Where to find it:
You can run A/B tests on standard campaigns, but the real power lies in the Automation Builder.
Testing Capabilities:
ActiveCampaign allows you to set up “Conditional Content” and “Split Actions” within automations. You can:
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Test Automation Paths: Send new leads down two different email sequences automatically. After 30 days, you can check which sequence resulted in more “Deals Won” in the integrated CRM.
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Test Email Content: Similar to others, but with the ability to automatically tag winners and move them to different pipelines based on their behavior.
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Predictive Sending: ActiveCampaign uses machine learning to predict the best time to send to each contact, effectively running constant send-time tests for you.
Why it’s a winner:
If your goal isn’t just to send a newsletter, but to move leads through a sales pipeline, ActiveCampaign offers the most robust A/B testing for automation mapping. You aren’t just testing a single email; you are testing a journey.
6. ConvertKit: The Creator’s Choice
For bloggers, podcasters, authors, and creators, ConvertKit is the dominant player. It focuses on simplicity and deliverability. Its A/B testing features are tailored specifically for audiences who rely on content and trust-building rather than flashy sales.
Where to find it:
ConvertKit offers “Visual Automations” where you can create split tests easily using a drag-and-drop interface.
Testing Capabilities:
ConvertKit’s testing is unique because it prioritizes subscriber engagement over sales data (though it integrates with e-commerce tools). You can test:
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Subject Lines: Standard.
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Content: Test two different writing styles or lead magnet deliveries.
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Visual Automations: You can create a split in your funnel where subscribers are sent to different sequences based on which link they click in a test email.
Why it’s a winner:
ConvertKit’s interface is the least intimidating for creators who are new to split testing. It uses a simple “Optimize For” dropdown (clicks or opens) and allows you to set the test duration easily. Plus, because ConvertKit is built for creators, it handles large text-based newsletters exceptionally well, ensuring your tests aren’t skewed by deliverability issues.
Honorable Mentions
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Brevo (formerly Sendinblue): Excellent for transactional emails and SMS. They offer A/B testing on subject lines and send times, though their content testing is more limited compared to the e-commerce giants.
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GetResponse: A veteran in the space offering robust A/B testing, including testing landing pages attached to your emails. It’s a great all-in-one marketing hub.
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Campaign Monitor: Known for beautiful templates. They offer robust A/B testing, particularly for enterprise clients, allowing testing of up to 10 different subject lines or content variations simultaneously.
How to Choose the Right Software for Your Needs
You now know where to find these tools, but how do you choose?
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If you sell physical products: Go with Omnisend or Klaviyo. You need to test revenue, not just open rates. Klaviyo is better for high-volume, sophisticated stores; Omnisend is better for growing stores that want ease of use with SMS built-in.
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If you are a service provider or consultant: Go with ActiveCampaign or ConvertKit. You need to test nurturing sequences that build trust over time, not just one-off promotional blasts.
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If you are a local business (restaurant, gym, real estate): Go with Constant Contact. You don’t need to test 10 different variables; you just need a simple, supported way to see if “Grand Opening” or “50% Off” works better as a subject line.
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If you are a beginner: Go with Mailchimp. Its free tier often includes A/B testing, allowing you to learn the principles of split testing without a monthly subscription cost.
Conclusion
Finding email marketing software with A/B testing features is not difficult—most platforms offer it. The challenge lies in finding the software that tests the right things for your business model.
Don’t settle for a platform that only tests subject lines. Look for a tool that allows you to test content, offers, send times, and—most importantly—automation flows. The brands that win in email marketing aren’t the ones with the biggest lists; they are the ones that know their audience best.
By leveraging the A/B testing capabilities in platforms like Omnisend, Klaviyo, or ActiveCampaign, you stop guessing what your audience wants and start giving it to them consistently.
Ready to stop guessing and start growing? Choose a platform from the list above, run your first split test this week, and let the data drive your next sale.
