Google Analytics 4

Koryla sends experiment data to GA4 via the Measurement Protocol — a server-to-server API that doesn't require the gtag.js snippet on your page.

Setup

You need two values from your GA4 property:

Measurement ID — found in Admin → Data Streams → your stream. Looks like G-XXXXXXXXXX.
Measurement Protocol API secret — in the same screen, scroll to Measurement Protocol API secrets → create a new one and copy the value.

Enter both in Dashboard → Integrations → Google Analytics 4 and toggle it on.

What gets sent

Koryla fires a experiment_viewed custom event on every new variant assignment:

{
  "name": "experiment_viewed",
  "params": {
    "experiment_id": "a1b2c3...",
    "experiment_name": "Homepage CTA Test",
    "variant_id": "x9y8z7...",
    "variant_name": "Blue button"
  }
}

Analyzing results in GA4

Go to Explore → Free form and configure:

Dimensions: experiment_name, variant_name
Metric: conversions, sessions, or your goal metric
Filter: event name = experiment_viewed

This gives you a breakdown of impressions and conversion rates per variant.

Notes

Events are fired once per visitor — returning visitors with an existing ky_ cookie do not generate a second event.
The Measurement Protocol sends events as anonymous (no client_id linkage to browsing sessions). Use experiment_name and variant_name as dimensions to slice data.
GA4 can take up to 24 hours to show custom events in the UI for the first time.