Email marketing tools do more than send messages — they run the behind-the-scenes systems that keep online stores growing. While beautiful templates and clever subject lines grab attention, what really drives conversion happens in the backend: data syncing, automation logic, segmentation, and deliverability.
Two names dominate the conversation when it comes to performance and functionality — Omnisend and Klaviyo. They both promise to help eCommerce brands sell more through email and SMS, but how they do it under the hood is what separates them.
In this article, we’ll look closely at Klaviyo vs Omnisend, focusing on how each platform handles the technical parts that directly affect sales and customer experience.
- Data: The Foundation of Every Campaign
The strength of any email platform starts with how it collects and uses data.
Klaviyo connects deeply with eCommerce platforms like Shopify, BigCommerce, and WooCommerce. Once integrated, it automatically pulls detailed customer data — browsing behavior, purchase history, product views, and even abandoned carts. This rich data allows marketers to build complex audience segments and send highly targeted messages.
On the backend, Klaviyo uses event-based tracking, meaning every customer action (like viewing a product or starting checkout) is stored as an event. These events can trigger automations or be combined with other data to create dynamic segments. It’s very flexible but can feel complex for beginners.
Omnisend, on the other hand, focuses on accessibility. Its data syncs smoothly with major eCommerce platforms too, but it structures that information in a more user-friendly way. Instead of needing to build everything from scratch, Omnisend provides pre-set segments such as “recent buyers,” “inactive subscribers,” or “cart abandoners.”
- Automation: The Heart of Conversion
Both platforms shine in automation — the feature that actually drives repeat sales and customer retention.
In Klaviyo, automations (called “flows”) are built around detailed triggers and conditions. You can stack filters, A/B test branches, and control timing with precision. For example, you could create a flow that sends one version of an abandoned cart email if the customer viewed high-value products and another if they viewed sale items.
From a backend perspective, Klaviyo’s automation engine runs on a rule-based logic that’s updated in real time. It uses customer events to determine the next step in a flow the moment that event happens. This means messages are highly personalized — but it also requires careful setup.
Omnisend takes a slightly different approach. Its automation system uses visual workflows that are simpler to navigate. You can create triggers based on events (like sign-ups or purchases) and add channels like SMS and push notifications in the same workflow.
Omnisend’s backend prioritizes speed and reliability over complexity. It uses prebuilt workflow templates for key use cases — welcome series, cart recovery, post-purchase follow-ups — all optimized for conversion.
- Segmentation and Personalization
Effective segmentation is what separates good email campaigns from great ones.
Klaviyo’s segmentation engine is highly detailed. You can combine data points like “opened an email in the last 30 days,” “purchased a product over $50,” and “lives in California.” It’s ideal for brands that have large lists and want precision targeting.
Technically, Klaviyo stores segment data dynamically. This means each time an email is sent, segments are recalculated in real time to ensure accuracy. It’s powerful but can use more system resources, which may slightly affect loading times for massive lists.
Omnisend’s segmentation model is built for quick execution. You can set up rules based on purchase frequency, product type, location, or engagement level. Its backend updates segments at regular intervals rather than every second, balancing accuracy with performance.
It’s less granular than Klaviyo, but for most eCommerce brands, the available options cover nearly every practical use case.
- Deliverability and Infrastructure
No matter how good your email looks, it won’t convert if it lands in spam. Deliverability depends heavily on how a platform manages sending servers, authentication, and reputation.
Klaviyo manages its own email infrastructure, giving it fine control over sender reputation. Users get automatic DKIM and SPF setup for authentication, and high-volume senders can request dedicated IPs. Its backend system groups senders by performance, isolating accounts with poor deliverability to protect others.
Omnisend also manages its infrastructure in-house but focuses on stability and simplicity. It offers strong sender authentication out of the box, and its backend prioritizes steady IP warm-up for new users. It’s built for smaller businesses that need reliable delivery without technical maintenance.
- Reporting and Optimization
After sending, analytics show how well your campaigns performed — and how to improve them.
Klaviyo tracks engagement across every flow and segment in granular detail. You can measure how each email or SMS step affects total revenue, not just clicks or opens. Its backend stores historical event data, allowing long-term analysis and cohort tracking.
Omnisend’s reporting is more focused on clarity. It shows key metrics like sales, click rates, and conversions in simple dashboards. The backend aggregates results across channels to show how email, SMS, and push messages work together.
If you need deep data modeling, Klaviyo’s reporting system has more layers. But if you want straightforward performance insights, Omnisend is faster to interpret.
Final Thoughts
When comparing Klaviyo vs Omnisend, both tools have strong technical foundations — they just cater to different types of users.
In the end, both are powerful email engines — but how you use them depends on your comfort with data and automation depth. Whether you prefer Klaviyo’s precision or Omnisend’s simplicity, the real goal stays the same: creating messages that not only convert but keep customers coming back.
