Meta lead form + Conversions API eliminated conversion loss from ad blockers. CR grew from 2.8% to 3.9%.
The task
The campaign launched from scratch: the advertiser had no buying history in this geo. Needed to find out why Meta's optimization algorithm was underperforming and recover conversion data for users lost to ad blockers.
We worked the "Lead Gen" vertical in the Italy market. Payment model — CPL per lead, main sources — Meta Ads (lead form).
How we did it
We split the work into several parallel tracks.
- Diagnosed that the client's original setup relied entirely on browser-pixel tracking — users with ad blockers or iOS tracking restrictions simply vanished from the conversion data.
- Switched to Meta's native lead form, removing the landing-page step entirely.
- Connected the server-side Conversions API so conversion events were sent directly from the client's CRM rather than from the browser.
What went wrong
The bottleneck turned up somewhere we didn't expect. Meta's optimization algorithm was training on an incomplete conversion picture — users blocked by extensions or iOS tracking restrictions weren't making it into the data, and nobody had noticed.
Pairing Meta's native lead form with the server-side Conversions API made it possible for the first time to correctly count users affected by ad blockers, straight from the client's CRM.
The result
The result was a controllable volume with predictable economics. Over the 2025: roi — 215%, cr after capi — 3.9%, cr uplift — +39%.
CR grew from 2.8% to 3.9% — a 39% relative improvement, and almost all of that gain came from a more complete and accurate dataset for the algorithm, not targeting or creative changes.
What we took away
- Browser-pixel-only tracking systematically loses users with ad blockers and iOS restrictions, skewing the data the algorithm trains on.
- The server-side Conversions API paired with a native lead form brings users invisible to the browser pixel back into optimization.
- More complete data for the algorithm can drive a bigger conversion gain than targeting or creative changes.
These numbers belong to one specific setup, geo, and buying period. Economics will differ on another offer or in another season — we always recalculate them before launch.