Heureka Verified by Customers runs via an iframe pixel that Adblock Plus, uBlock Origin, and Brave block by default. Real numbers: on a typical CZ store, 20–30% of reviews are missing because of ad-blockers. Server-side solves both — the events and the feed.
How the Heureka iframe pixel fails
The standard "Verified by Customers" integration instructs stores to insert an iframe after an order:
<iframe src="https://www.heureka.cz/direct/dotaznik/?id=ORDERID&email=BASE64..." width="0" height="0"></iframe>The filter ||heureka.cz/direct/dotaznik^ in EasyList CZ blocks 100% of such requests. The conversion doesn't reach the Heureka system → the "Rate your purchase" email is never sent.
The server-side path
Heureka has an API key for Verified by Customers that allows a server-to-server call. That is ad-blocker-resistant and goes from your domain.
- In the Heureka admin → API → create a key for Verified by Customers
- In
/dashboard/platforms/heureka/enter the API key + the email template ID - The DataNostro engine sends a conversion event after every purchase
- Heureka sends the questionnaire to the customer 5–14 days after purchase (configurable)
First-party Heureka feed
A second typical problem: the Heureka feed at shop.cz/heureka.xml is often cached for 12 hours in Cloudflare or the Shoptet CDN. The Heureka crawler then hits stale data there.
The Heureka feed proxy power-up in DataNostro:
- Serves the feed from your tracking subdomain (e.g.
feed.store.cz/heureka.xml) - Caches for 1 h (configurable)
- Validated against the current Heureka XSD
- Bonus: the POAS Data Feed power-up automatically reads the
cogsormargincolumn from it
Heureka.cz vs. Heureka.sk
If you sell in both CZ and SK, you have two separate Heureka accounts (different domain, different API keys, different feeds). DataNostro supports them in parallel — there are two Heureka instances in the dashboard, one marked cz, the other sk.
Verification
In the Heureka admin → API → Logs you'll see the server-side hits. Heureka doesn't provide EMQ-like metrics, but you can watch the orders → reviews ratio (before/after the server-side migration).
Conclusion
The Heureka iframe pixel is 2014 technology. Ad-blockers, ITP, and iOS updates chip away at it year after year. The server-side path via DataNostro brings back the 20–30% of missing reviews and strengthens your ranking in the "Verified by Customers" league. Integration details →