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Setting up server-side conversion tracking
Browser tracking is losing data every year. Moving measurement to your own server recovers a good deal of it, and raises questions worth answering honestly.
Key points
- Server-side tracking recovers data lost to blockers and browser limits, not data lost to refused consent.
- It gives you control over what is sent to third parties, which is its main privacy advantage.
- Consent still governs everything; the server is not a way around it.
Measurement in the browser has been degrading for years: ad blockers remove the scripts, browsers shorten cookie lifetimes, and platform privacy features block third-party requests. Depending on audience, 15 to 40 per cent of events are lost.
What moving to the server changes
In the classic setup, the visitor's browser sends data directly to each advertising platform. In a server-side setup, the browser sends data to a server you control, which then forwards a defined subset onwards.
Three consequences follow.
Fewer losses. Requests to your own domain are less often blocked than requests to known advertising hosts.
More control. You decide what is forwarded. In the browser setup, a third-party script sees everything on the page, including data you never intended to share.
Better data quality. Server-side events can be enriched with information the browser does not have, such as whether an order was later cancelled.
The strongest argument for server-side measurement is not recovering signal. It is that you finally know what leaves your site.
What it does not change
It does not create a legal basis. If a visitor refuses tracking, no event may be forwarded, whatever the technical route. Systems configured to send data despite refusal are unlawful and, in the event of a complaint, straightforward to prove.
It also does not fix bad measurement. A wrongly defined conversion event stays wrong on a server.
The setup, in outline
- A container or endpoint on a subdomain of your own domain.
- Consent state read before anything is forwarded, per purpose.
- Events sent from the browser to your endpoint with a stable event identifier.
- Forwarding to each platform, with only the fields that platform needs.
- Deduplication, so an event sent both browser-side and server-side is counted once.
Point five is where most implementations break. Without a shared event identifier, conversions get double-counted and every downstream number is wrong.
Costs and effort
| Item | Typical |
|---|---|
| Initial setup | 2 to 5 days of specialist work |
| Hosting | £20 to £150 a month |
| Ongoing maintenance | half a day a quarter |
| Documentation and records | one day, once |
The last row is not optional. Your records of processing must reflect what is actually sent where.
The data protection paperwork
Server-side measurement makes you the controller of a processing step you previously outsourced without noticing. That means: an entry in your records of processing, a processor agreement with the hosting provider, a defined retention period, and an updated privacy notice describing what is forwarded to whom.
Doing this properly is a day of work and removes an exposure most browser-side setups carry silently.
Frequently asked questions
Does this circumvent consent?
No, and using it that way is unlawful. Consent is required regardless of where the code runs.
Is it worth the effort?
Above roughly £5,000 monthly ad spend, usually yes. Below that the setup cost outweighs the recovered signal.
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