Marketing Platform Comparison
They look similar, both send clever, behaviour-based messages. In practice they're built for different businesses. Here's how to tell which one your messaging actually needs.
Go with Customer.io if you're a product or software business where the moments that matter happen inside an app, sign-ups, feature adoption, milestones, churn signals, and you've got some technical help to wire up the data.
Go with Klaviyo if you sell products online — Shopify, BigCommerce, WooCommerce — and you want store-aware email and SMS that work straight out of the box, without leaning on developers.
Our honest take Choose by where your customer data lives and what your key moments are — a checkout, or a step inside a product — not by comparing feature lists. The right pick depends on your business model.
Product-led and SaaS businesses
Ecommerce and online stores
Things people do inside your product or app
Things people do in your store, browsing, carting, buying
Email, SMS, push, in-app and webhooks
Email and SMS, purpose-built for ecommerce
Event-based, fully customisable, built around product behaviour
Store-data-driven, built around purchase and browsing behaviour
Campaign and conversion tracking tied to product events
Revenue attribution tied directly to store sales
Transparent, profile-based; starts at $100/month
Scales with contacts; return is visible through revenue tracking
If the important moments happen in a store — browsing products, adding to cart, completing a purchase — Klaviyo plugs straight into your shop and starts working. The connection to Shopify, BigCommerce and WooCommerce is deep, and the flows you build are powered by real store data from day one. If those moments happen inside a product or app — someone signs up, activates a feature, hits a usage milestone, or goes quiet — Customer.io is built to listen for exactly those signals. It sends across email, SMS, push and in-app, all from the same workflow, triggered by the same customer events.
Klaviyo's strength is how quickly it connects to ecommerce platforms. You install it, connect your store and within minutes your customer data is flowing, purchase history, browsing activity, cart events, lifetime value. The setup is fast because the data model is built around how online stores work.
Customer.io's strength is flexibility. You define the events and attributes that matter to your product, onboarding steps, feature usage, subscription changes, anything your app tracks, and build messaging around them. That flexibility means more initial setup, but it also means the platform adapts to your business rather than the other way around.
Klaviyo focuses on email and SMS for ecommerce, and does both exceptionally well in the same flow. A cart recovery email followed by an SMS reminder two hours later, all triggered by the same store event, is the kind of coordination that drives real revenue for online stores.
Customer.io covers more channels, email, SMS, push notifications, in-app messages and webhooks, all in one workflow builder. For product businesses where customer engagement happens across multiple touchpoints (not just inbox and phone), having everything in one flow makes the messaging smarter and more connected.
Klaviyo's pricing scales with your contact list, and the return is visible through built-in revenue attribution, you can see exactly what each flow and campaign earns. For ecommerce businesses, that visibility often makes the investment easy to justify.
Customer.io charges by profiles and includes unlimited events and attributes on all plans, which matters for product businesses that track a lot of user behaviour. There are no surprise charges for data volume. The starting price is higher than Klaviyo's entry point, but for a SaaS or product business sending across multiple channels, the value is in the flexibility and the breadth of what's included.
This isn't a "which is better" decision, it's a "which fits your business model" decision. A Shopify store and a SaaS product have fundamentally different customer journeys and these two platforms were designed around those different journeys. Choosing the right one is less about features and more about where your customers are and what the important moments look like.
Do you sell products in a store, or run a product or app people log into?
Store → Klaviyo. Product or app → Customer.io.
Where do your most important customer moments happen — at checkout, or inside a product?
Checkout → Klaviyo. Inside a product → Customer.io.
Do you need push notifications or in-app messages as part of your flows?
Yes → Customer.io handles these natively.
We work with both platforms. Customer.io is what we use for our own messaging, and Klaviyo is a preferred partner we set up for ecommerce clients regularly. That means we can look at your business and tell you straight which one fits, then set it up so the right message reaches the right person at the right moment.
Occasionally, but for most teams it's one or the other. Picking the right fit from the start saves time, cost and complexity. We'll help you figure out which one makes sense.
It's more flexible, which means it rewards some technical setup to get the most from it, defining your events, connecting your data sources, mapping your customer journey. That's the part we handle.
Almost always Klaviyo. The store connection is deep, the setup is fast and the flows are built around exactly how online stores work.
It's strongest for product-led and SaaS businesses, but it also works well for any business where the key customer moments happen digitally, memberships, apps, marketplaces, subscription services. If your customer journey is event-driven, Customer.io is worth a look.