Klaviyo is the most-installed app on Shopify, found on more than one in three stores we scan, and it is the runaway leader in email marketing. It earns that position with a specific strength: it treats Shopify as a live data feed rather than a contact importer, so purchases, cart additions, and browsing behavior flow straight into its segmentation engine and build your audience automatically. The verdict upfront: for a store with repeat purchasers and a real email list, Klaviyo is the strongest retention platform on Shopify, and it holds a 4.7 out of 5 App Store rating. The honest catches are cost, which scales with your list, and the fact that its power is wasted if you never build the flows. It is also worth knowing that its share, while huge, has been slipping lately.

If you are a repeat-purchase, direct-to-consumer brand that lives on email and SMS, Klaviyo is usually the right call and the one to grow into. If you are pre-launch, tiny, or unlikely to configure it properly, you may be paying for infrastructure you will not use. The sections below use live detection data to show how dominant it is, what makes it different, what it costs, and where it falls short.

Key Takeaways
1
Klaviyo is an email and SMS marketing app, and it is the single most-installed app on Shopify as well as the clear leader in email marketing.
2
Its edge is architecture: it uses Shopify as a live data feed, so purchase, cart, and browsing signals build segments automatically instead of relying on form fills.
3
It holds a 4.7 out of 5 App Store rating, but its monthly detection has been slipping recently, a trend worth watching for an app at this scale.
4
It is expensive on the wrong footing: pricing scales with your contact list, and an under-configured account means paying for power you are not using.
5
Best for repeat-purchase, direct-to-consumer brands in apparel, health and beauty, and subscriptions that have a real email list and will build proper flows.
Klaviyo Email Marketing and SMS app on the Shopify App Store showing a 4.7 rating and free to install
Klaviyo on the Shopify App Store, with its 4.7 rating and free-to-install pricing. Source: Shopify App Store.

What is Klaviyo?

Klaviyo is an email and SMS marketing platform for Shopify. Store owners use it to collect subscribers, segment their audience, and send automated flows and campaigns, from welcome series and abandoned-cart reminders to post-purchase and win-back messages. It also handles SMS, sign-up forms and popups, and reporting that ties messages back to revenue. It is the most-installed app in our dataset, and its nearest email competitor is on a fraction as many stores. Here is how dominant it is.

34.4%
Share of stores in our dataset
#1
Popularity rank
9.2
Avg apps on their stores

How popular is Klaviyo?

Klaviyo is not just the leading email app, it is the most-detected app of any kind on Shopify. It is used many times more than the next email marketing app in the ranking, and it also sits near the top of the stack for subscription and multichannel stores. In short, it is the default retention infrastructure for a large slice of serious Shopify merchants.

#1 app in our dataset
Klaviyo is the most-detected app in our dataset.
#1 Email Marketing app
Klaviyo is the most-used Email Marketing app in our dataset.
6.1x more used than Omnisend Email Marketing & SMS
Stores in our dataset use Klaviyo 6.1 times more than Omnisend Email Marketing & SMS, the next Email Marketing app in the ranking.

There is one caveat in the trend, and we will not hide it. Klaviyo’s share of the stores we scan each month has slipped rather than grown recently, which is a meaningful move for an app of this size. It is still dominant, but the direction is worth watching, most likely a sign that cost-conscious merchants are testing cheaper alternatives.

FebMarAprMayJunJul41.1%49.7%

Klaviyo has climbed from 41.1% to 49.7% of Shopify stores in our dataset over recent months.

What makes Klaviyo different?

Most email apps import your contacts and let you send to them. Klaviyo does something more useful: it plugs into Shopify as a live data feed. Purchase events, cart additions, browsing behavior, and product-level interest all flow directly into its segmentation engine with no manual wiring beyond the initial connection.

The practical result is that audience-building happens automatically, off real customer behavior rather than form fills. You can target people who bought a specific product, who browsed but did not buy, or who have not ordered in ninety days, and trigger messages off those signals. That depth is why Klaviyo stores tend to run heavier app stacks than the average store, sitting alongside reviews, support, analytics, and subscription tools. These are not stores testing an idea, they are stores running a retention operation.

Klaviyo features

Klaviyo bundles a full retention toolkit rather than just a newsletter sender, which is a big part of why serious stores standardize on it.

  • Email and SMS: run both channels from one audience, so a customer is not messaged twice for the same event.
  • Behavioral segmentation: build segments off live Shopify signals like purchases, cart activity, and browsing.
  • Automated flows: welcome, abandoned cart, post-purchase, win-back, and back-in-stock sequences that run on their own.
  • Sign-up forms and popups: capture subscribers on-site and feed them straight into flows.
  • Reporting tied to revenue: see what each flow and campaign actually earns, not just opens and clicks.
  • Predictive data: estimated lifetime value and next-order timing to sharpen targeting.

The toolkit is deep, which is its strength and its trap: the value only appears once the flows are built. An account with no flows configured is an expensive contact list.

How much does Klaviyo cost?

Klaviyo is free to install and includes a free tier for a small list, so you can set it up and start building flows before you pay anything. Once you grow past the free allowance, pricing is usage-based and scales with the size of your contact list and how you use email and SMS.

That model is the honest sticking point. Klaviyo can get expensive as your list grows, and the bill rises whether or not your flows are earning their keep. The way to make it pay is to treat the list as an asset you actively work, not a number you let inflate. Build and maintain the core flows, prune inactive contacts, and the returns justify the cost. Install it, let the list balloon, and never send a considered campaign, and it becomes one of the priciest apps on your bill for no reason.

Which themes and apps run with Klaviyo?

Because we detect both themes and apps, we can see the company Klaviyo keeps. On the theme side it is genuinely universal, showing up most on Shopify’s free Dawn theme and then across the popular premium themes, which reflects how widespread it is rather than any special pairing. Here are the themes most commonly running it.

Dawn: 13.24%Dawn13.2%Prestige: 6.13%Prestige6.1%Impulse: 6.09%Impulse6.1%Impact: 4.2%Impact4.2%Horizon: 3.25%Horizon3.3%Broadcast: 2.94%Broadcast2.9%Shrine PRO: 2.92%Shrine PRO2.9%Symmetry: 2.23%Symmetry2.2%Focal: 1.71%Focal1.7%Concept: 1.65%Concept1.7%
RankTheme% of stores
1Dawn13.2%
2Prestige6.1%
3Impulse6.1%
4Impact4.2%
5Horizon3.3%
6Broadcast2.9%
7Shrine PRO2.9%
8Symmetry2.2%
9Focal1.7%
10Concept1.7%

On the app side, Klaviyo rarely runs alone. The stores that use it most often also run a reviews app for social proof, a subscriptions tool, customer support software, and analytics, the full retention stack. That is the tell that Klaviyo is chosen by stores treating email as a core channel rather than an afterthought. For the full breakdown of themes, paired apps, and store types, see the live Klaviyo usage statistics.

What kinds of stores use Klaviyo?

Klaviyo’s user base is concentrated, not spread evenly across Shopify. Apparel and accessories alone accounts for around half the Klaviyo stores we classify, followed by health and beauty and then food and drink, all categories built on repeat buying. Some of the biggest direct-to-consumer beauty and lifestyle brands run on it.

By business model, subscription stores are heavily represented, alongside multichannel sellers, which fits an app built around lifecycle messaging and retention. The pattern is clear: Klaviyo is the default for high-repeat, direct-to-consumer, email-dependent merchants, and less relevant for a one-off-purchase or very small store.

Where Klaviyo falls short

The honest downsides are cost and complexity, not capability. Klaviyo is powerful, but that power sits behind a usage-based bill that grows with your list, so a large, poorly worked list can cost real money for little return. Under-configured accounts are common, where a merchant installs Klaviyo, never builds the flows, and pays for infrastructure they are not using. The app does not hold your hand into value; you have to go and get it.

The slipping adoption trend fits this picture. For merchants who never operationalized it, or who have grown cost-sensitive, cheaper email apps become tempting. None of this means Klaviyo is the wrong choice, it means it is the wrong choice for stores that will not use it properly. Go in planning the flows and the list hygiene, not just the install.

One worry with any marketing app is speed, since it is easy to assume that adding another tool slows a store down. For Klaviyo the data says otherwise. Compared fairly against similar stores on the same theme and with a similar number of products and apps, the ones running Klaviyo actually pass Google’s Core Web Vitals speed test more often, not less: about 72% versus 61% for comparable stores without it (among stores large enough to appear in Google’s Chrome UX Report). Klaviyo itself is not the bottleneck.

Does Klaviyo slow a store down?

Compared only against stores on the same theme, running the same number of apps and carrying a similar catalogue, stores with Klaviyo installed pass Core Web Vitals 12.8 points higher of the time (11,256 comparable stores across 813 matched groups).

ComparisonWith KlaviyoWithoutStores compared
Like-for-like stores71.6%58.8%11,727 with · 12,971 without
All stores, unmatched70.2%64.9%14,420 with · 17,198 without

Who should use Klaviyo?

Klaviyo is the right pick if you are a repeat-purchase, direct-to-consumer brand with a real and growing email list, especially in apparel, health and beauty, or subscriptions, and you are ready to build proper flows. For that store, no other Shopify email app matches its depth of Shopify-native segmentation, and the returns comfortably justify the cost.

Pass, or at least wait, if you are pre-launch, still under a few hundred subscribers, or not going to configure it beyond the install. In that case, start on the free tier and grow into it, but plan the flows before you start paying for the list. A cheaper, simpler email app may serve a very small or one-off-purchase store better until retention becomes a real lever. At the other extreme, a large brand where SMS is the primary channel may prefer a dedicated SMS-first platform like Attentive.