What a postback actually does
Server-to-server postbacks are the plumbing of performance marketing. A plain-language walkthrough of click IDs, parameters and why S2S beats pixels.
If performance marketing has a nervous system, it is the postback. It is the message that tells a network, "the click you sent us became a conversion." Without it, nobody gets paid correctly.
The journey of a click ID
- A user clicks a tracking link. The tracking system generates a unique click ID and redirects the user to the advertiser's landing page or app store listing, passing the click ID along.
- The advertiser (or its MMP) stores the click ID with the user's session or install.
- When the user converts, the advertiser's system calls the network's postback URL, including that click ID and details such as the event name and value.
- The network matches the click ID to the original click — and therefore to the publisher, sub-ID and placement that produced it.
A postback might look like this:
https://track.example.net/postback?click_id=7f3a91&event=registration&payout=2.40¤cy=USDWhy server-to-server beats pixels
Browser pixels fire from the user's browser. They are blocked by ad blockers, broken by privacy features, and lost when users switch devices or apps. Server-to-server (S2S) postbacks travel directly between servers, so they do not depend on the user's browser at all.
S2S is also easier to secure: postback endpoints can require a secret token and reject calls from unknown IPs.
Parameters worth standardizing
| Parameter | Purpose |
|---|---|
| click_id | Joins the conversion to the original click |
| sub1…sub5 | Publisher-defined IDs: placement, creative, campaign |
| event | Which conversion happened (install, lead, purchase) |
| payout / value | What the event is worth, for reconciliation |
| currency | Avoids silent conversion errors |
Agreeing on these names up front saves hours of reconciliation later.
Attribution windows
A postback only counts if it arrives within the agreed attribution window — for example, a purchase within 7 days of the click. Windows should match the real buying cycle: too short and genuine conversions are lost; too long and unrelated conversions get credited.
For step-by-step setup, see the conversion tracking guide.
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