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S2S postbacks: how to set them up and what breaks most often

29.05.2026 · 8 min read · DAY30 editorial team

Article illustration: S2S postbacks: how to set them up and what breaks most often

Nine out of ten disputes about numbers are not a dispute about honesty but a different reading of events. Postbacks exist precisely so that both sides count the same thing at the same moment in time.

How it is set up

The team hands over a link with tags. The operator stores the tag at registration and, when an event occurs — registration, first deposit, repeat deposit — sends a server request to the team's endpoint with the identifier and the parameters. It all happens between servers; the player's browser is not in the chain and blocks nothing.

Minimum set of parameters

ParameterWhat it carries
click_idThe click identifier; everything else is reconciled against it
eventreg / ftd / redep
amountDeposit amount
currencyCurrency and exchange rate date
statusapproved / rejected / pending
player_idAnonymised player identifier for cohorts

Five typical breakages

1. click_id is lost on redirect

An intermediate page or a link shortener strips the parameters. Check it with a test click followed by a deposit — it has to arrive intact.

2. The event is sent only once

If the team's server returns an error and the operator does not retry, the event is lost for good. Retries on an interval are required.

3. The deposit arrives before the registration

An event race when registration and payment happen fast. The receiving side has to be able to process an ftd with no preceding reg.

4. Currency with no exchange rate

An amount in reais converted at the rate on the reconciliation date rather than the payment date gives a discrepancy of a few percent — and an argument out of nowhere.

5. Rejected FTDs are not resent

The operator rejected the deposit as fraud but did not send the status. The team counts it as its own and invoices for it.

How to accept the work

Before buying starts we run an end-to-end test: a click on a tagged link, a registration, a real minimum deposit, a rejection of a test deposit. All four events have to match on both sides by identifier, amount and time. Until they match, any volume is a future dispute.

Which affiliate platforms we integrate with and how we work through discrepancies — on the page “Terms”.

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