Tracking & optimisation · also called postback URL, S2S postback, server-to-server tracking, callback
Postback (server-to-server tracking)
A postback is a message sent directly from one company's server to another's to report that a tracked click produced a conversion or revenue.
A postback is one computer telling another, "that click you sent me, number ABC123, just earned 80 cents." It travels server to server, with no browser involved, so ad blockers, cookie restrictions and closed tabs cannot interfere with it.
The mechanism has two halves. On the way out, the click carries a unique Click ID, which the receiving side stores. On the way back, when something valuable happens, the receiver calls a prepared web address (the postback URL) with that ID and usually an amount. In search arbitrage a typical chain has two hops: the feed provider posts events or revenue to the arbitrageur's tracker, and the tracker posts conversions onward to the traffic source, often via its Conversions API.
Postbacks are only as good as the data behind them. Feed revenue is often available with a delay and as an estimate, so the values posted may be provisional. Postback addresses must also be kept private: anyone who can call one can fake results, which is one route to fake conversions.
Think of it like this
It is a cloakroom ticket. You hand over your coat and get a number. Later, the number alone is enough to reunite the two.
An example
Say a click arrives with ID abc123. The visitor clicks a feed ad. The provider calls the tracker's postback address with that ID and a payout of 0.80, and the tracker records $0.80 against the exact ad and placement that produced the visit.
Related terms
Tracker (campaign tracking platform)
A tracker is software that records every click an arbitrageur buys, matches it to the revenue it later earns, and reports profit by campaign, ad and keyword.
Click ID
A click ID is a unique code an ad platform or tracker attaches to each ad click so that later events can be matched back to that exact click.
Conversions API (CAPI)
The Conversions API is Meta's server-to-server interface for sending conversion events and their values to Meta directly, without relying on the visitor's browser.
Tracking pixel
A tracking pixel is a small piece of code on a web page that tells an ad platform, through the visitor's browser, that a page view or action took place.
Sub ID
A sub ID is a custom label a publisher passes to a feed or network with each visit, so reported revenue can be broken down by that label.
Revenue reporting delay
Revenue reporting delay is the gap between a visitor clicking a feed ad and the arbitrageur seeing, and later confirming, the revenue for that click.