Sklik is the biggest blind spot of every global sGTM host. Stape, Addingwell, Google Cloud Platform — none of them supports Sklik conversions natively. Here's how to deploy it on server-side GTM via DataNostro in an afternoon.
Why Sklik has no CAPI
Sklik historically has no Conversions API like Meta or Google Ads. Instead it has two paths:
- The retargeting code (client-side JS) — a pixel for retargeting cookies
- Server-to-Server conversions via the URL endpoint
http://c.imedia.cz/checkConversionwith the parameters id, value, currency, transactionID
Most stores only handle retargeting; server-side conversions are neglected in practice — which is why the data in Sklik campaigns isn't trusted. iOS, ad-blockers, and ITP throttle the client-side pixel; the server-side path stays intact.
What you'll need
- A Sklik account with an active campaign
- A server-side GTM container (DataNostro setup in 5 min)
- A web GTM container — if you don't have one yet, Setup Assistant generates one for Shoptet / Upgates / FastCentrik
Step 1: Sklik conversion code
In the Sklik admin → Conversions → Create conversion:
- Type: Server-to-server
- Conversion value: Dynamic (we'll pass it from the store)
- Currency: CZK
- Attribution model: Last-click (default)
Sklik generates a retargeting ID for you (e.g. 123456). Copy it.
Step 2: DataNostro dashboard
In /dashboard/platforms/seznam-sklik/ enter the Sklik retargeting ID and save. No Access Token, no OAuth — Sklik uses the retargeting code directly in the URL.
Step 3: Deduplication via transaction_id
The key thing: the Sklik retargeting code on the site and the server-side conversion must send the same transaction_id. Sklik then deduplicates — no double counting.
Send the transaction_id in the dataLayer from the store, the server-side reads it and passes it to the Sklik S2S endpoint.
Step 4: Test
Sklik has its own debugger — Conversions → Conversion debugger. Send a test order and you'll see the server-side hit in the format:
http://c.imedia.cz/checkConversion?id=123456&hodnota=2490&mena=CZK&transactionID=order_001Common mistakes
- The retargeting cookie doesn't match. Sklik retargeting runs client-side and sets a session cookie. The server-side conversion must come from the same session, otherwise Sklik won't attribute it.
- Value in hundredths. Sklik wants the value in CZK, not in hellers. If you use Stripe, divide by 100.
- UTF-8 in the transactionID. Sklik only accepts ASCII — use a numeric order ID, no customer emails or special characters.
What's next
Sklik is just the start. Server-side via DataNostro also gives you Heureka Verified, GA4 deduplication, Meta CAPI, and 14 more platforms for free. Setup Assistant generates a GTM container in 5 minutes. Learn more →