Klaviyo Custom Events: How to Track the Ecommerce Behaviors Shopify Doesn't Send by Default

Your Klaviyo-Shopify integration tracks transactions — Placed Order, Started Checkout, Viewed Product. It misses the behavioral signals that actually differentiate a retention program: subscription pauses, review submissions, loyalty tier changes, quiz completions. Custom events fill that gap, and each one unlocks flows and segments your competitors cannot build with default data alone.

This is a ranked implementation guide. Ten custom events, prioritized by revenue impact relative to technical lift, with the exact payload structure for each and the specific flow or segment it powers. Not API docs. Not a feature overview. A build list for the events that make your Klaviyo instance smarter than the one running on default data.

Last updated: August 2026

What Does Klaviyo Track from Shopify by Default?

The standard Klaviyo-Shopify integration automatically syncs transactional and browsing events — Placed Order, Started Checkout, Added to Cart, Viewed Product, and a handful of others. These events cover the purchase funnel from product discovery through completed order, but they miss every behavioral signal that happens outside of a direct buying action.

Shopify is the ecommerce platform that serves as the primary storefront and order management system for most DTC brands using Klaviyo. If you have set up the default Shopify-Klaviyo event tracking, your instance already receives:

• Placed Order / Ordered Product: completed purchases with line-item detail
• Started Checkout: checkout initiation with cart contents
• Added to Cart: product additions (requires on-site tracking active)
• Viewed Product: product page visits
• Fulfilled Order / Cancelled Order / Refunded Order: order lifecycle updates

That covers who bought, who almost bought, and who browsed. It does not cover who paused their subscription, who left a five-star review, who hit Gold tier in your loyalty program, or who completed your product quiz and selected "sensitive skin." Those behaviors carry high intent and reveal customer state changes that transactional data never captures.

How Do Custom Events Unlock Flows and Segments Default Data Can't?

Every custom event you send to Klaviyo appears as a custom metric, which means it becomes a flow trigger, a segment condition, and a data point feeding predictive models. The event itself is the signal. The properties you attach determine what you can personalize, filter, and act on downstream — a bare event with no properties is a trigger with no intelligence.

Custom metric is Klaviyo's term for any event that does not come from a native integration. The Klaviyo Track API is the server-side endpoint for sending custom event data into your Klaviyo account. When you send a "Subscription Paused" event through the Track API, Klaviyo creates a custom metric by that name. Klaviyo Flows are automated email and SMS sequences triggered by specific events or customer behaviors. From that custom metric, you can build a flow triggered by Subscription Paused, create a segment of profiles who triggered it in the last 30 days, and use the event's properties to personalize email content dynamically.

The downstream value compounds. Custom events feed Klaviyo's predictive analytics — more behavioral data means more accurate CLV predictions, better churn risk scores, and tighter expected-next-order-date calculations. Behavioral segmentation is the practice of grouping customers based on their actions and interactions rather than demographic attributes alone. Custom events enable behavioral segments impossible with default data: "reviewed but never repurchased," "paused subscription in last 30 days," or "completed quiz but did not buy."

Every custom event you track needs a planned downstream use: a flow it triggers, a segment it defines, or a predictive model it feeds. Tracking data without a use case is instrumentation theater — it looks sophisticated but generates zero revenue.

How Should You Prioritize Which Custom Events to Build?

Use a two-axis framework that ranks each event by revenue impact against implementation complexity. This produces four tiers — Quick Wins, Strategic Builds, Easy Adds, and Backlog — giving you a clear build sequence instead of a flat list where a fifteen-minute webhook setup sits next to a custom app that takes a developer two weeks.

Plot every potential custom event on two axes: how much revenue it can influence through the flow it triggers or the segment it enables, and how much technical work it takes to implement. A webhook is an automated HTTP notification sent in real time from one application to another when a specified event occurs — most implementations below use webhooks to relay data from third-party tools into Klaviyo.

Quick Wins — High Revenue Impact, Low Complexity

• Subscription Paused: webhook from Recharge or Skio triggers a pause-save flow that can recover churning subscribers
• Review Submitted: webhook from Yotpo, Stamped, or Judge.me triggers post-review flows and builds a "reviewed but never repurchased" segment
• Quiz Completed: form submission event from your quiz tool triggers personalized recommendation flows based on quiz answers

Strategic Builds — High Revenue Impact, Higher Complexity

• Loyalty Tier Changed: webhook from LoyaltyLion or Smile.io triggers tier-specific welcome flows and enables VIP segmentation by loyalty status
• Out-of-Stock Variant Viewed: custom on-site tracking powers a back-in-stock flow at the variant level, not just the product level
• Subscription Cancelled: webhook from Recharge or Skio triggers a cancellation-save or winback flow with reason-specific messaging

Easy Adds — Lower Revenue Impact, Low Complexity

• Wishlist Added: client-side event builds interest-graph segments and enables price-drop notifications
• Loyalty Points Milestone: webhook from loyalty platform triggers celebration flows and redemption reminders

Backlog — Lower Revenue Impact, Higher Complexity

• Subscription Product Swapped: webhook from subscription platform tracks product preferences but rarely triggers a standalone flow
• Custom Bundle Configured: complex client-side tracking yields interesting data but costs more to build than its immediate flow value justifies

Start with the Quick Wins. They take hours, not weeks, and each one unlocks a flow that generates revenue the day it goes live.

Get your free lifecycle audit — we'll score your Klaviyo setup against the custom event priority matrix and show you which events would have the highest revenue impact for your store

Which Custom Events Should You Implement First?

Subscription Paused, Review Submitted, and Quiz Completed are the three events that consistently deliver the fastest return for DTC brands on Klaviyo. Each requires minimal technical work — typically a webhook configuration, not custom development — and each unlocks a specific flow that default Shopify data cannot trigger.

Subscription Paused

When a subscriber pauses through Recharge, Skio, or Loop, the subscription platform can fire a webhook to Klaviyo. This creates a Subscription Paused custom metric that triggers a Pause Save flow — a sequence designed to offer alternatives before the subscriber cancels entirely.

Event properties are the key-value pairs attached to a custom event that determine what you can filter and personalize downstream. For Subscription Paused, include:

• subscription_id: the unique identifier for linking back to the subscription platform
• product_name: what they subscribed to, enabling product-specific save messaging
• pause_reason: why they paused, enabling reason-specific branching in the flow
• subscription_value: monthly value, enabling prioritization of high-value saves
• subscription_duration_months: how long they have been subscribed, so a 12-month subscriber gets different messaging than someone one month in

Flow it triggers: a 3-message Pause Save sequence offering skip, swap, or frequency adjustment — with a conditional split on pause_reason so "too much product" gets a frequency change offer while "too expensive" gets a one-time discount on the next order.

Segment it enables: "At-Risk Subscribers" — anyone who triggered Subscription Paused in the last 30 days, excluded from aggressive promotional sends and prioritized for retention-focused campaigns.

Review Submitted

Review platforms like Yotpo, Stamped, and Judge.me can send a webhook to Klaviyo when a customer submits a review. The Review Submitted event turns every review into a segmentation and flow trigger.

Properties to include:

• review_rating: the star rating (1–5), enabling splits between promoters and detractors
• product_name: which product was reviewed
• review_body_length: word count of the review, since longer reviews signal higher engagement
• has_photo: whether the review includes a photo, identifying your strongest advocates

Flow it triggers: a conditional post-review flow. Five-star reviewers get a referral program invitation and a cross-sell offer for complementary products. Three-star-and-below reviewers get a customer service outreach email before any marketing follow-up.

Segment it enables: "Reviewed but Never Repurchased" — customers who took the time to review but have not ordered again. This segment responds well to cross-sell campaigns because they have already demonstrated product satisfaction.

Quiz Completed

Product recommendation quizzes (via Octane AI, Typeform, or custom builds) collect zero-party data that default tracking never captures. When a quiz is completed, fire an event to Klaviyo with the quiz results as properties.

Properties to include:

• quiz_result_category: the primary recommendation, such as "sensitive skin" or "beginner"
• recommended_products: the specific product IDs or names the quiz recommended
• quiz_answers: key answers informing personalization, like skin type, goals, or experience level
• completed_purchase: whether they bought after the quiz, identifying quiz-completers who need follow-up

Flow it triggers: a personalized recommendation flow where email content is dynamically populated based on quiz_result_category. A "sensitive skin" result generates emails featuring gentle formulations, while "anti-aging" results feature retinol and peptide products.

Segment it enables: "Quiz Completed, No Purchase" — the highest-intent non-buyers on your list. They told you what they want. They just have not bought it yet.

Loyalty Tier Changed (Strategic Build)

When a customer moves up or down a loyalty tier in LoyaltyLion or Smile.io, the platform fires a webhook to Klaviyo. This event powers tier-specific experiences that basic purchase data cannot deliver.

Properties to include:

• new_tier: the tier they moved into (Silver, Gold, Platinum)
• previous_tier: where they came from, enabling upgrade versus downgrade branching
• loyalty_points_balance: current points for dynamic email content showing available rewards
• tier_benefits: what they now have access to, populating the tier-welcome email with specific perks

Flow it triggers: a tier celebration flow for upgrades (congratulations, new benefits, exclusive access) and a re-engagement flow for downgrades showing how close they are to regaining their previous tier.

How Do You Send Custom Events to Klaviyo?

Custom events reach Klaviyo through the Track API — a server-side endpoint that accepts an event name, a customer identifier, and a properties object in a single API call. Most DTC implementations use webhooks from third-party tools routed through a middleware layer or sent directly to the endpoint.

Klaviyo's Track API is the server-side endpoint that receives custom event data and creates or updates the corresponding custom metric in your account. Each call requires three components: the event name (which becomes the custom metric name), a customer identifier (typically an email address), and a properties object containing the event-specific data you want to track.

The implementation path depends on where the event originates:

1. Webhook from a third-party tool. Recharge, Yotpo, LoyaltyLion, and most SaaS tools offer webhook configurations. Point the webhook at a serverless function (AWS Lambda, Cloudflare Worker) or middleware platform (Make, Zapier) that reformats the payload and forwards it to Klaviyo's Track API. This covers subscription events, review events, and loyalty events.
2. Direct API call from your backend. For events originating in your Shopify backend or custom app — like quiz completions or inventory-triggered events — your development team calls the Track API directly from server-side code.
3. Client-side JavaScript. Klaviyo's JavaScript SDK can track events from the browser for interactions like wishlist additions or out-of-stock variant views. Client-side tracking is simpler to implement but less reliable than server-side, since ad blockers and browser restrictions can prevent events from firing.

Server-side tracking via webhooks or direct API calls produces higher-quality data. For any event that drives a revenue-generating flow, prefer server-side implementation. For the full endpoint specification, authentication setup, and rate limit details, see Klaviyo's Track API reference documentation.

For a walkthrough of configuring flow triggers once your custom metrics are flowing into Klaviyo, see our complete Klaviyo flow setup guide.

What Properties Make a Custom Event Payload Actually Useful?

A custom event payload is only as valuable as what you can do with its properties downstream. Every property should serve at least one of three purposes: enabling a flow filter or conditional split, populating dynamic email content, or powering a segment definition. Properties that serve none of these are dead weight in your data model.

When designing your payload, categorize each property by its downstream job:

• Flow filter properties: values used in conditional splits (review_rating greater than 3, subscription_value above $50, loyalty_tier equals "Gold"). These must be clean, consistently formatted, and reliably populated — a missing value breaks your split logic.
• Dynamic content properties: values pulled into email templates (product_name, recommended_products, tier_benefits). These power personalization. A Loyalty Tier Changed event without the new_tier property means your tier-welcome email cannot tell the customer what tier they reached.
• Segment definition properties: values used in Klaviyo segment conditions (quiz_result_category equals "sensitive skin," pause_reason equals "too expensive"). These build the behavioral segments that sharpen your campaign targeting over time.

A common mistake is sending minimal events — just the event name and an email address with no properties. This gives you a trigger but nothing to act on. The difference between a bare Review Submitted event and one carrying review_rating, product_name, and has_photo is the difference between sending everyone the same thank-you email and routing five-star photo reviewers to a referral invitation while three-star reviewers get a service recovery message.

Can Custom Events Trigger Klaviyo Flows?

Yes. Every custom event that reaches Klaviyo creates a custom metric, and any custom metric can serve as a flow trigger. Configure this in the flow builder by selecting "Metric" as the trigger type, choosing your custom metric from the dropdown, and adding trigger filters based on the event's properties to control which profiles enter the flow.

The trigger configuration follows the same pattern as default metrics. When building a Pause Save flow triggered by Subscription Paused, you add filters like "subscription_value is greater than $30" to prioritize high-value subscribers, or "subscription_duration_months is greater than 6" to tailor messaging for long-tenured subscribers differently than recent ones.

One implementation detail worth noting: Klaviyo processes custom metrics in near real-time, but a brief delay exists between the API call arriving and the flow triggering. For most use cases this is negligible. For time-sensitive events — like an out-of-stock variant view where you want to fire a notification the moment inventory is replenished — test the actual latency in your account before building time-critical logic around it. Back-in-stock flows convert at 10–25% according to Blossom's benchmark data, making variant-level tracking one of the highest-ROI Strategic Build events on the priority matrix.

For details on flow trigger configuration and conditional split logic for custom metrics, see Klaviyo's flow creation guide.

Start with Three Events, Then Compound

You do not need all ten custom events live next month. You need the three Quick Wins — Subscription Paused, Review Submitted, and Quiz Completed — wired up with the right properties and connected to flows that generate revenue the week they go live.

Custom events compound. Once your Klaviyo instance has richer behavioral data, your predictive analytics, segmentation, and flow personalization all improve simultaneously. The gap between your retention program and a default-data-only competitor widens with every event you add — not linearly, because each new data point makes every existing flow and segment smarter.

Start with the Quick Wins. Prove the revenue impact. Then work through the Strategic Builds as your technical capacity allows. The Priority Matrix gives you the sequence. The payload structures give you the specification. The flow mapping gives you the revenue case.

Want us to build this for your brand? Book a free strategy call — we'll map out which custom events would have the highest impact for your Klaviyo setup and build the implementation plan

FAQ

Below are answers to the most frequently asked questions about implementing custom events in Klaviyo for Shopify-based DTC brands — covering which events to prioritize, how to send them through the Track API, what the default integration already tracks, and how custom metrics function as flow triggers and segment conditions.

What custom events should I track in Klaviyo?

Start with events that trigger revenue-generating flows your default Shopify integration cannot power. Subscription Paused, Review Submitted, and Quiz Completed are the highest-ROI starting points for most DTC brands because they combine low implementation complexity with immediate downstream value through the flows and segments they enable.

How do I send custom events to Klaviyo from Shopify?

Route events through Klaviyo's server-side Track API. For events from third-party tools like Recharge or Yotpo, configure the tool's webhook to send data through a middleware layer (Make, Zapier, or a serverless function) that reformats the payload and forwards it to Klaviyo. For events from your Shopify store directly, your development team calls the Track API from server-side code.

What events does Klaviyo track from Shopify by default?

The standard integration tracks Placed Order, Ordered Product, Started Checkout, Added to Cart, Viewed Product, Fulfilled Order, Cancelled Order, and Refunded Order. These cover the purchase funnel but miss subscription changes, review activity, loyalty actions, quiz completions, and other behavioral signals that occur outside of direct buying actions.

Can I trigger Klaviyo flows with custom events?

Yes. Every custom event creates a custom metric in Klaviyo, and any custom metric works as a flow trigger. Select "Metric" as the trigger type in the flow builder, choose your custom metric, and add filters based on the event's properties to control which profiles enter the flow and how conditional splits route them.

How do I track subscription events in Klaviyo with Recharge?

Recharge offers webhook configurations for subscription lifecycle events including paused, cancelled, and product swapped. Configure each webhook to fire to a middleware endpoint that transforms the Recharge payload into Klaviyo Track API format, mapping the subscriber's email and relevant subscription properties like pause_reason, subscription_value, and product_name.

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