What Is Klaviyo? A Guide for Ecommerce Brands

If you sell online, you've almost certainly heard the name. Klaviyo shows up in Shopify app recommendations, in agency pitch decks, and in the tech stack of nearly every fast-growing ecommerce brand you admire. But "email and SMS platform" is a thin description for what it actually does — and that vagueness is exactly why so many store owners sign up, poke around for twenty minutes, and never come back.

This guide explains what Klaviyo is, how it's different from the email tool you might already be using, and whether it's worth the switch for your store. No jargon, no affiliate spin — just a clear look at the platform and what it's actually built to do.

Klaviyo is a marketing platform built specifically for ecommerce. It sends email and SMS, but unlike a general-purpose tool like Mailchimp or Constant Contact, every part of it is designed around one job: turning store data into revenue.

That distinction matters more than it sounds. A generic email platform knows whether someone opened a newsletter. Klaviyo knows whether they then bought the £85 jacket they viewed twice, abandoned in their cart, and clicked through from a follow-up email three days later. It connects directly to your store — Shopify, BigCommerce, WooCommerce, Magento — and pulls in orders, products, browsing behaviour and customer profiles in real time.

In practice, that means you're not just sending emails. You're building automated sequences that react to what a real person did on your site, and you can measure exactly how much revenue each one produced, down to the individual flow and email.

Underneath the interface, Klaviyo is built around three things: profiles, events, and flows.

Profiles

Every person who lands on your site, signs up to your list, or buys from you gets a profile. That profile accumulates data over time — what they've bought, how much they've spent, what they've browsed, which emails they've opened, and any custom properties you choose to track.

Events

Events are the actions that build those profiles: "Placed Order", "Viewed Product", "Started Checkout", "Subscribed to List". Klaviyo tracks these automatically once it's connected to your store, and you can add custom events for anything specific to your business.

Flows and campaigns

Campaigns are one-off sends — a Black Friday email, a new collection announcement. Flows are automated sequences triggered by an event or a condition: someone abandons a cart, a new customer makes their first purchase, a subscriber hasn't opened anything in 90 days. Once a flow is built, it runs without you touching it again, reacting to each person's behaviour individually.

For most stores, email is the highest-margin channel they have. There's no ad spend, no bidding war, no platform taking a cut — you're messaging people who already know who you are. Klaviyo is built to make that channel work as hard as possible, for a few specific reasons:

• Native store integration. Product images, prices and stock levels sync automatically into emails — no manual updating when a product sells out or a price changes.
• Behavioural segmentation. You can target "people who've bought twice but not in 60 days" or "browsed the sale category but didn't purchase" without writing a line of code.
• Revenue attribution. Every flow and campaign shows exactly how much revenue it generated, so you're optimising against real numbers, not opens and clicks.
• SMS in the same platform. Email and SMS share the same customer data and the same flow builder, so you're not stitching together two disconnected tools.

Klaviyo's feature list is long, but most of the value sits in a handful of areas:

Flows (automation)

Pre-built and custom automations that run on autopilot: welcome series, abandoned cart, browse abandonment, post-purchase, win-back. For most stores, flows generate a disproportionate share of total email revenue relative to the time spent building them.

Segmentation

Dynamic, real-time groups built from any combination of behaviour, purchase history and engagement. A segment updates itself as people's behaviour changes — no manually exporting and re-importing lists.

Forms and sign-up units

Pop-ups, embedded forms and flyouts for growing your list, with built-in A/B testing on copy, design and timing.

Reporting

Revenue per recipient, attributed revenue per flow, deliverability metrics and list growth — all in one dashboard, without needing to cross-reference your store's analytics separately.

The platform itself doesn't make you money. The flows and segments you build inside it do.

Klaviyo is built for stores with recurring transactional data — ecommerce, subscription businesses, anything where "Placed Order" is a meaningful, repeatable event. If that's you, the behavioural data it captures is genuinely difficult to replicate elsewhere.

It's a weaker fit for businesses without that transactional layer — a local service business taking enquiries through a contact form, for instance, gets little benefit from Klaviyo's ecommerce-specific features and would be better served by a simpler tool.

It's also worth being honest about effort. Klaviyo rewards stores that actually build out flows and segments properly. Brands that connect it, send a generic newsletter, and leave the rest on autopilot tend to get underwhelming results — not because the platform doesn't work, but because it was never set up to work.

Klaviyo charges based on the number of profiles in your account — broadly, contacts you're actively marketing to — rather than a flat monthly fee. SMS is billed separately, based on message volume. There's a free tier for very small lists, and cost scales up as your list grows.

The practical implication: list hygiene matters. Suppressing unengaged profiles you'll never convert keeps your bill proportional to the audience that's actually worth marketing to, rather than paying to message people who haven't opened an email in two years.

The setup sequence that tends to work, in order:

• Connect your store and confirm data is syncing — orders, products and customer profiles.
• Set up sender authentication (SPF, DKIM, DMARC) so your emails land in the inbox, not spam.
• Build your foundational flows first: welcome series, abandoned cart, post-purchase.
• Add a sign-up form to start growing your list with intent.
• Layer in segmentation and campaigns once the automated revenue base is in place.

We cover the full process in detail in our welcome flow setup guide.

Plenty of stores run Klaviyo entirely in-house, and for a small list with simple needs, that's often the right call. The platform's interface is genuinely accessible to non-technical marketers, and the built-in flow templates give you a reasonable starting point without writing anything from scratch.

Where it gets harder is maintenance. Flows need revisiting as your product range changes, segments drift out of date as customer behaviour shifts, and deliverability needs occasional attention as your sending volume grows. None of this is difficult individually, but it adds up, and it's the part that tends to get deprioritised when the person running Klaviyo also has five other jobs.

That's usually the point at which stores either dedicate someone internally to own it properly, or bring in an agency or freelancer to manage it ongoing — not because the platform demands it, but because someone needs to actually keep iterating on it for the revenue to keep growing.

Treating it like a newsletter tool

The single biggest waste of Klaviyo's potential is using it purely for one-off campaigns and ignoring flows. Flows run continuously and typically outperform campaigns on revenue per recipient by a wide margin, because they're triggered by genuine purchase intent.

Skipping authentication setup

Sending from an unauthenticated domain tanks deliverability fast. It's a ten-minute setup that gets skipped constantly, usually because nobody flags it during onboarding.

Over-segmenting too early

Building forty hyper-specific segments before you have the list size or data to support them adds complexity without adding revenue. Start broad, narrow down as patterns emerge.

Ignoring SMS compliance

SMS carries stricter consent requirements than email in most jurisdictions. Getting opt-in language wrong is a compliance risk, not just a deliverability one.

Is Klaviyo only for Shopify stores?

No. Klaviyo integrates with Shopify, BigCommerce, WooCommerce, Magento and others. Shopify's integration is the deepest and most commonly used, but it's not a requirement.

Can I migrate from Mailchimp or Klaviyo's other competitors?

Yes. Klaviyo has built-in migration tools for contacts, and most flow logic needs to be rebuilt natively rather than imported, since automation structures don't transfer cleanly between platforms.

Do I need a developer to set it up?

Not for most stores. The standard ecommerce integrations are plug-and-play. Custom events or non-standard platforms occasionally need development work, but the core setup is designed for marketers, not engineers.

How long until I see results?

Flows start generating revenue almost immediately once live, since they're triggered by existing site traffic and purchase behaviour. Campaigns and list growth compound more slowly, typically over several months.

Conclusion

Klaviyo isn't just "email marketing software" — it's a system for turning your store's own data into a channel that runs largely on autopilot once it's built properly. The platform itself is only half the story; the flows, segments and sends you put inside it are what actually move revenue.

If you're evaluating whether to switch, the question isn't whether Klaviyo is good — it's whether you (or whoever runs it) will put in the setup work to use what it's actually built for.