Klaviyo Connector for OpenCart — events, profiles and subscriptions from your store to Klaviyo

Klaviyo Connector for OpenCart connects a store on OpenCart 4, 3 or 2.3 to Klaviyo over the official REST API. It sends Klaviyo what flows and segments are built on: product views, the cart, the checkout start with a link that brings the cart back, orders with everything in them and the customer profile — and subscribes to marketing only those who ticked the box themselves. Running WooCommerce? See Klaviyo Connector for WooCommerce.

How it was tested, honestly. Klaviyo has no sandbox, so the module is built on the official Klaviyo API documentation (revision 2026-07-15) and tested end to end against a simulation of that API — the formats of events, subscriptions, catalog calls and error answers checked against the documentation — on OpenCart 4.1 (PDO), 4.0.2.3, 3.0.5.0 and 2.3.0.2, on nginx with PHP-FPM and on Apache, next to the stock checkout and CatCode One Page Checkout. It has not run on a live Klaviyo account yet — try it on yours in the 7-day Pro trial. The log shows every request and Klaviyo’s answer, and if Klaviyo answers differently from its documentation, we fix it quickly.

What the customer sees

• Nothing extra on the storefront. klaviyo.js loads asynchronously, Klaviyo forms (popups, embedded) show up as you set them in Klaviyo. A page never waits for Klaviyo: all requests go after the page is served.
• Marketing consent is a separate, unticked box. Where the checkout already has OpenCart’s own newsletter box (OpenCart 4, One Page), that box is the consent. Where it does not (guest checkout in OpenCart 3 and 2.3), our box sits under the email field, in the storefront language; the text can be changed per language.
• The abandoned cart comes back. The customer clicks the link in the Klaviyo email and the cart with the same products and options opens even on another device, for 30 days.
• Cookies by the rules. The “wait for cookie consent” mode loads klaviyo.js only after consent in Cookiebot, CookieYes or your own banner.

What the store gets

• “Save and check” verifies the key against the Klaviyo account, fills in the public key for klaviyo.js and loads all your lists. A Klaviyo error is shown in plain words with the HTTP code.
• The private key is stored encrypted (AES-256 with HMAC), never printed back into the form and never written to the log.
• Placed Order and Ordered Product come from the same order history call OpenCart itself uses: the stock checkout, One Page, payment callbacks and a status change in the admin give the event once. The total is in the order currency; lines carry the image, link, categories, brand and options, plus the discount with the coupon code, tax, shipping and addresses.
• Started Checkout carries the cart link and the cart lines, one event per customer and cart content a day, as soon as the email is known: the customer is logged in or typed it at checkout.
• The customer profile: name, E.164 phone by the address country, address and language — inside the order event. A phone Klaviyo would refuse is left out and the event still goes.

• A queue instead of calls during the purchase. An event is written to the queue and sent after the page answers, by a background call from the next storefront page or by the cron. A Klaviyo rate limit (429) pauses exactly as long as Klaviyo asks, server errors retry with growing delays, a refused request keeps Klaviyo’s answer in the log.
• A key without a needed scope (403) does not stop everything: only requests of that kind wait, the admin tells which scope is missing, all other events keep going.
• A copy of the store on another address (staging, a move) sends nothing until you confirm it is the live store.

How it works — step by step

1. Key. In Klaviyo: Settings → API keys → Create Private API Key (Full, or Custom with access to Events, Profiles, Lists, Subscriptions, Catalogs and read access to Accounts).
2. Connection. Extensions → Modules → Klaviyo Connector → Connection: paste the key, “Save and check”, choose the list for subscribers.
3. Tracking and consent. Tracking and Consent tabs: which events to send, the cookie mode, the box text for each language.
4. Flows in Klaviyo. The Started Checkout, Placed Order and Viewed Product metrics appear in Klaviyo with the first events — abandoned cart, post-purchase and browse abandonment flows are built on them.
5. Pro. Order lifecycle, Catalog and History tabs: statuses for the events, catalog sync, past orders and subscribers.

Under the hood

• Klaviyo REST API, revision 2026-07-15: Create Event, Bulk Subscribe / Unsubscribe, catalog items, variants and categories, Accounts, Lists. Authorization with the Klaviyo-API-Key header.
• No duplicates: every event has a stable unique_id (installation prefix + order number), so a repeated request or a repeated order history call does not create a second event in Klaviyo.
• Stock OpenCart events: the module listens to addHistory in OpenCart 4 and addOrderHistory in 3.x and 2.3, so it sees orders from any checkout and any payment that goes through the core.
• No writes to the OpenCart session: the visitor state (email, consent, cart snapshot) lives in the module’s own table, so parallel checkout requests are never overwritten.
• A Pro gate without bricking: when the trial ends, only the Pro features stop.
• Removing the module clears its events, cron jobs and permissions; the module tables with the settings copy and the cart restore links of emails already sent stay, so updates and reinstalls lose nothing. To remove the data completely, drop the oc_cc_klaviyo_* tables.

How to install

1. OpenCart 4: Extensions → Installer → upload cc_klaviyo.ocmod.zip (do not rename the archive) and click Install. OpenCart 3: Extensions → Installer → cc_klaviyo-oc3.ocmod.zip, then Extensions → Modifications → Refresh. OpenCart 2.3: upload the contents of the upload/ folder from cc_klaviyo-oc23.ocmod.zip to the store root (FTP or the hosting file manager) — the 2.3 Installer does not copy files without FTP set up.
2. Extensions → Extensions → Modules → Klaviyo Connector → Install, then Edit.
3. Connection: the Klaviyo private key, “Save and check”, the subscriber list, status Enabled.
4. For Pro: paste the licence key from the email after payment or click “Start the 7-day trial” on the Licence tab.