Klaviyo

What Is Klaviyo?

Klaviyo is an email and SMS marketing platform built specifically for e-commerce. Founded in 2012 and publicly listed since 2023, Klaviyo set itself apart by treating customer data as the core of marketing: it ingests detailed behavioral and transactional signals from a store and uses them to power highly personalized email and text campaigns. It is especially dominant in the Shopify ecosystem, where its deep integration makes it a default choice for direct-to-consumer brands that want product-aware automations and revenue-attributed reporting.

Answer-first: if a website loads JavaScript from static.klaviyo.com (commonly a klaviyo.js), exposes a klaviyo or _learnq global in the console, and sends tracking beacons to a.klaviyo.com carrying a company_id, the site is using Klaviyo to track visitors and drive email/SMS marketing.

A note on sourcing: Klaviyo's e-commerce focus, its prominence on Shopify, and its 2023 IPO are well documented in Klaviyo's public filings and broad industry coverage. Specific market-share figures vary by source and period, so this profile characterizes Klaviyo's position qualitatively rather than quoting a fixed number. Verify current features against the official Klaviyo documentation.

How Klaviyo Works

Klaviyo is best understood as a customer-data-driven marketing engine attached to a store. The flow:

1. Track. A small Klaviyo script (klaviyo.js, served from static.klaviyo.com) runs on the storefront and records browsing behavior, product views, and identified-customer activity, sending events to Klaviyo via beacons to a.klaviyo.com. Each account is identified by a public company_id (also called the public API key, often a six-character string).
2. Sync. Klaviyo's e-commerce integration (notably with Shopify) imports orders, customers, products, and cart data, enriching each profile with purchase history and lifetime value.
3. Segment. Real-time segments update automatically based on behavior and transactions, such as repeat buyers, browse-abandoners, or lapsed customers.
4. Flow. Flows (Klaviyo's automations) trigger email and SMS messages from events like cart abandonment, browse abandonment, purchase, and win-back, with conditional splits and timing.
5. Predict and measure. Predictive features estimate metrics such as expected lifetime value and churn risk, and Klaviyo attributes revenue back to specific campaigns and flows.

On the website, the visible footprint is the Klaviyo script and any embedded signup form or pop-up. The data warehouse, segmentation, and sending all live inside Klaviyo.

The two-sided nature of Klaviyo's data collection is worth understanding because it explains the signals you observe. On one side is onsite tracking: the klaviyo.js script watches what a visitor does in the browser (pages viewed, products browsed, forms submitted) and reports those events to a.klaviyo.com. On the other side is the server-to-server integration: Klaviyo pulls authoritative records like orders and customers directly from the store's platform via its API, independent of the browser. The onsite script is what you fingerprint from the outside; the API sync is invisible to a page inspection but is what makes Klaviyo's personalization so precise. When the two are stitched together by the shared company_id and a customer identity, Klaviyo can connect an anonymous browsing session to a known buyer and a full purchase history.

A subtle point that aids detection: Klaviyo maintains a legacy event queue named _learnq for backward compatibility, in addition to the modern klaviyo object. Older or partially migrated integrations may push events onto _learnq (an array) while newer code uses klaviyo.push(...). Seeing either is a positive signal, and seeing both is common on sites that have lived through Klaviyo's API evolution.

How to Tell if a Website Uses Klaviyo

Klaviyo leaves clear, specific footprints that are easy to confirm with a browser and even easier with server-side analysis.

Script domains and network requests

Open DevTools, go to the Network tab, reload, and filter for klaviyo. The two domains to watch for:

static.klaviyo.com     (the tracking/onsite script, e.g. /onsite/js/klaviyo.js)
a.klaviyo.com          (event and identify beacons)

The onsite script is frequently loaded with the account's public key in the query string, for example klaviyo.js?company_id=ABC123. Beacons to a.klaviyo.com carrying a company_id parameter are a definitive signal.

JavaScript globals in the console

Klaviyo exposes recognizable globals. In the DevTools Console, type each of these:

klaviyo
_learnq

The modern object is klaviyo (with methods like identify, track, and push), while _learnq is the long-standing legacy queue array Klaviyo uses to collect events before the script fully loads. Seeing either returned as an object/array rather than undefined confirms Klaviyo is active.

The company_id parameter

The company_id (public API key) is the thread that ties the signals together. You will see it in the script URL, in the beacon payloads to a.klaviyo.com, and sometimes in embedded form configuration. It is a public identifier (safe to expose), so finding it in the page is expected, not a misconfiguration.

HTML forms, cookies, and markup

Klaviyo signup forms and pop-ups render containers with klaviyo-prefixed classes (for example, klaviyo-form-XXXX). Klaviyo also sets cookies in the browser to identify and dedupe visitors across sessions; check Application > Cookies for Klaviyo-related entries. The combination of a klaviyo-form element, the onsite script, and tracking cookies is a strong, layered confirmation.

Tools that automate detection

• View Source / DevTools confirm the static.klaviyo.com script, the klaviyo/_learnq globals, and klaviyo-form markup.
• Network tab reveals beacons to a.klaviyo.com and the company_id parameter.
• Wappalyzer and similar extensions detect Klaviyo automatically.
• Because pop-ups can be delayed or exit-intent triggered and scripts can be injected dynamically, server-side analysis is the most dependable method. StackOptic inspects scripts, globals, request beacons, and embedded forms from the server side to confirm Klaviyo reliably. For manual technique, see how to find what email marketing platform a website uses and, since Klaviyo so often rides on a store, how to find out what ecommerce platform a website uses.

Key Features

• Deep e-commerce integration. First-class sync with Shopify and other platforms for orders, products, carts, and customers.
• Email and SMS in one platform. Unified messaging so flows can mix channels for the same customer.
• Real-time segmentation. Segments that update instantly from behavioral and transactional data.
• Flows (automations). Cart abandonment, browse abandonment, welcome, post-purchase, win-back, and review-request automations with conditional logic.
• Predictive analytics. Estimates for customer lifetime value, churn risk, and timing to drive proactive marketing.
• Onsite tracking and forms. The klaviyo.js script and native pop-ups/embeds for capture and behavior tracking.
• Revenue attribution. Reporting that ties revenue back to specific campaigns and flows.

Pros and Cons

Pros

• Built for e-commerce, with personalization that references specific products and behaviors.
• Powerful, real-time segmentation and flexible automation logic.
• Email and SMS managed together against a single customer profile.
• Strong revenue attribution that ties marketing to dollars.
• Excellent Shopify integration that is close to plug-and-play.

Cons

• Pricing scales with contact count and can become expensive for large lists.
• More complex and feature-dense than simple newsletter tools, with a steeper learning curve.
• Best value is realized by stores; non-commerce sites may not use most of its strengths.
• Heavy reliance on accurate data sync means integration issues can degrade targeting.

Klaviyo vs Alternatives

Klaviyo's closest comparisons are Mailchimp (broad, generalist), ConvertKit (creators), and platform-native tools like Shopify Email. The defining axis is depth of e-commerce personalization.

Capability	Klaviyo	Mailchimp	ConvertKit	Shopify Email
Best fit	E-commerce stores	SMBs, generalists	Creators	Basic Shopify sends
E-commerce personalization	Excellent	Good	Basic	Limited
SMS marketing	Strong	Limited	Limited	Limited
Predictive analytics	Yes	Some	No	No
Typical fingerprint	klaviyo.js / a.klaviyo.com	list-manage.com forms	convertkit.com forms	Shopify-native
Learning curve	Moderate	Low	Low	Low

If a store needs maximum behavioral personalization and SMS, Klaviyo is the leader. For a simpler, lower-cost generalist starting point, Mailchimp is the common alternative, especially for non-commerce or early-stage senders.

Use Cases

• Abandoned-cart recovery. Automated reminders that reference the exact products left behind.
• Browse-abandonment nudges. Follow-ups based on products a visitor viewed but did not add to cart.
• Post-purchase and win-back flows. Cross-sell, replenishment, and re-engagement timed to customer behavior.
• VIP and loyalty targeting. Segments built on predicted lifetime value and purchase frequency.
• Email + SMS coordination. Multichannel campaigns that reach the same customer through complementary channels.

Why Klaviyo Detection Matters for Site Analysis

Finding Klaviyo on a website is a strong commercial signal. Because Klaviyo is purpose-built for e-commerce and is especially entrenched on Shopify, its presence usually tells you the site is a serious online store investing in retention and behavioral marketing, not a casual newsletter. For competitive and market research, identifying Klaviyo (and distinguishing it from a generalist tool like Mailchimp) helps you gauge how sophisticated a brand's lifecycle marketing is and what kind of automation pressure their customers experience. For ecosystem and integration vendors, knowing a prospect already runs Klaviyo shapes whether and how a product should complement it.

Klaviyo is also one of the more dependable tools to fingerprint because its identifiers are specific and layered. The static.klaviyo.com onsite script, the klaviyo and _learnq globals, the beacons to a.klaviyo.com, and the company_id that threads through all of them rarely produce false positives. The familiar caveat applies to pop-ups and dynamically injected forms, which may not appear in a static source view, so the always-present script and globals are the most trustworthy evidence. Pairing Klaviyo detection with e-commerce platform detection (often Shopify) gives an even richer picture of the store's stack, which is exactly the kind of correlated analysis a server-side scan is built for.

Compliance Note

E-commerce marketing carries email and SMS obligations, and the two channels are not held to the same standard. CAN-SPAM (US) requires honest headers, a working unsubscribe, and a physical address for commercial email. SMS marketing is stricter: it additionally implicates consent rules (such as those associated with the TCPA in the US) and mobile-carrier requirements, so explicit, documented opt-in for texts is essential and quiet hours often apply. GDPR (EU/UK) generally requires a lawful basis and clear disclosure for marketing of either kind. Klaviyo provides consent tracking, separate email and SMS subscription states, quiet-hours controls, and unsubscribe handling to support these requirements, but lawful collection of consent and accurate privacy disclosures remain the sender's responsibility. This is a brief orientation, not legal advice.

Frequently Asked Questions

What is the fastest way to confirm a site uses Klaviyo?

Open the Console and check whether klaviyo or _learnq returns an object/array rather than undefined, then check the Network tab for static.klaviyo.com/onsite/js/klaviyo.js and beacons to a.klaviyo.com carrying a company_id. Any of these alone is suggestive; together they are conclusive.

Is it a security problem that the company_id is visible?

No. The company_id (public API key) is designed to be public and must appear client-side for tracking to work. The sensitive credential is the private API key, which is used only server-side and should never be exposed in the page.

Is Klaviyo only for Shopify?

No, but it is especially strong on Shopify. Klaviyo integrates with multiple e-commerce platforms and custom stores; the Shopify integration is simply the most polished and widely used.

How is Klaviyo different from Mailchimp?

Klaviyo is purpose-built for e-commerce, with deeper real-time segmentation, predictive analytics, and strong SMS. Mailchimp is a broader, more generalist marketing tool with an easier on-ramp and a generous free tier, but less specialized commerce personalization.

Does Klaviyo handle SMS as well as email?

Yes. Klaviyo manages email and SMS within the same platform and against the same customer profiles, so a single flow can coordinate both channels and avoid double-messaging the same person. SMS, however, has stricter consent rules than email and separate carrier requirements, so you must collect explicit text opt-in and configure subscription states correctly rather than reusing email consent.

Want to see whether a store runs Klaviyo, Mailchimp, or something else, plus the rest of its stack? Analyze the URL with StackOptic.