Why server-side for Klaviyo?
Klaviyo triggers flows and segmentation from events (placed order, viewed product, started checkout). If they're only sent from the browser via the client snippet, ad-blockers and ITP lose some of them — flows don't fire and email revenue drops. The Klaviyo Events API sends events server-side reliably.
How it works with DataNostro
The server-side GTM container sends the event straight to Klaviyo via the Events API — with the metric name, customer profile (email / phone / external_id), value and properties. The event arrives even without a running browser (e.g. server-side orders or store webhooks).
What gets sent to Klaviyo
- metric (event name) — Placed Order, Started Checkout, Viewed Product…
- profile — email, phone_number, external_id
- properties — items, categories, order value
- $value — revenue for reporting and CLV
- time — event time in ISO 8601
- unique_id — for idempotency (no duplicates)
Correct date format (ISO 8601)
Klaviyo expects the event time in ISO 8601 (e.g. 2026-06-09T12:00:00Z or with an offset +02:00). DataNostro normalises the date automatically, so you avoid the common error where Klaviyo rejects an event with an invalid timestamp.
Idempotency — no duplicate events
On retry or client + server overlap there's a risk of double-counting. DataNostro sends a unique_id (e.g. the order ID) that Klaviyo dedups on — one order = one Placed Order.
Setup in DataNostro — no developer
In Connections you enter the Klaviyo private API key and map store events. Works with the GA4 data layer and plugins (Shopify, WooCommerce). Done in minutes.
Proč Klaviyo přes DataNostro?
Reliable flow triggers
Server-side events fire abandoned-cart and post-purchase flows even where client-side fails.
E-commerce events
Viewed Product, Added to Cart, Started Checkout, Placed Order — the full funnel.
Profile data
Events are sent with the customer identifier for accurate segmentation.
No developer
Paste your Klaviyo API key in Connections — done in minutes.
Server-side tracking for all platforms
Jeden sGTM kontejner — všechny integrace na jednom místě.
Frequently asked questions
What is Klaviyo server-side tracking via the Events API? +
Events (Placed Order, Started Checkout…) are sent straight from your server to Klaviyo via the Events API instead of only the browser. They reliably trigger flows even where an ad-blocker blocks the client snippet.
What date format does Klaviyo require? +
ISO 8601, e.g. 2026-06-09T12:00:00Z (or with an offset +02:00). DataNostro normalises the timestamp automatically so Klaviyo won't reject an event for an invalid date.
How do I prevent duplicate events in Klaviyo? +
A unique_id (typically the order ID) is sent. Klaviyo dedups on it, so one order = one Placed Order even on retry or client + server overlap.
Which events are most often sent server-side? +
Placed Order (with $value for revenue), Started Checkout, Viewed Product, Added to Cart, Fulfilled Order. Server-side is most reliable for Placed Order, which drives post-purchase flows.
Do I need a developer? +
No. In Connections you enter the Klaviyo private API key and map events from the data layer / store plugin. No website code changes.
No missed Klaviyo trigger
Server-side Klaviyo Events API in minutes. Reliable flows, accurate data.