Conversion postback for CPA campaigns

A pay-per-result (CPA) campaign is paid for the conversions your tracking platform reports to SofAds. It takes two steps: hand our click ID to your platform in the landing URL, and let your platform call our postback URL, server to server, when a conversion happens.

1. Pass the click ID in the landing URL

Every QR scan gets its own click ID. Your tracking platform has to receive it on the click, so it can send it back with the conversion. On a pay-per-result campaign the wizard asks which tracking platform you use, and SofAds adds the click ID to your landing URL under that platform's parameter name:

https://network.example/click?offer_id=123&aff_click_id={CLICK_ID}

Tracking platform	Parameter SofAds adds	Sent back in the postback as
TUNE (HasOffers)	aff_click_id={CLICK_ID}	{aff_click_id}
Everflow	sub1={CLICK_ID}	{sub1}
CAKE	s2={CLICK_ID}	#s2#
Affise	sub1={CLICK_ID}	{sub1}
impact.com	subId1={CLICK_ID}	{SubId1}
AppsFlyer (app attribution links)	clickid={CLICK_ID}	{clickid}
Other	the parameter name you enter	your platform's macro for it

• Other: a name of letters, digits and _, starting with a letter, up to 64 characters, for example clickid or subid.
• Already in your URL? When your landing URL already has {CLICK_ID} somewhere, SofAds leaves it exactly as it is and adds nothing.
• CAKE uses s2, not s1: CAKE keeps s1 for steady values such as a source, and puts unique values in s2 to s5.
• The same tracking link can carry the other landing URL macros too, for example sub2={SOURCE_ID} to see results per source in your own platform.

The click ID step of a pay-per-result campaign: the tracking platform presets and Other

2. Your postback URL

The Conversion tracking page in the advertiser dashboard builds this URL for you, with your campaign's ID and your platform's placeholders already filled in. It looks like this:

https://t.sofadsrv.com/v1/postback?cid=cmp_7Kd2mQx9TfA3&key=YOUR_POSTBACK_KEY&click_id={aff_click_id}&event=purchase&txid={transaction_id}

Paste it into your platform's postback (server-to-server) settings and replace YOUR_POSTBACK_KEY with the campaign's key. The key is shown once, when you create it on the campaign; if you lost it, make a new one there, and the old one stops working.

cid is your campaign's ID as the dashboard shows it, starting with cmp_. Numeric IDs are refused.

Parameters

Parameter	Required	What it is
cid	yes	Your campaign's ID (cmp_ and 12 letters or digits).
key	yes	The campaign's secret postback key.
click_id	yes	The click ID from the landing URL, sent back by your platform.
event	no	The event name, for example purchase. Only the events chosen on the campaign are paid.
payout	no	Only for campaigns that pay the payout you report: a decimal amount in USD, capped at the campaign's maximum.
currency	no	USD, sent with payout. Other currencies are recorded but not paid.
txid	no	Your transaction ID. The same transaction counts once, however often it is sent.

GET and POST both work; on POST the parameters may also be a form body. When allowed IP addresses are set for the campaign, calls from other addresses are refused.

What we answer

Every answer is JSON with a status, and a reason when something is off:

{ "status": "accepted", "conversion_id": "0b6f3c3e-8a51-4c43-9e4d-2a8f0b7f1d6e" }

HTTP	status	Meaning
200	accepted	Recorded.
200	duplicate	Already recorded for this click and event, or this txid. Your platform can stop retrying.
200	rejected	The campaign can't take conversions: unknown_campaign (no campaign with this cid) or not_cpa (the campaign isn't pay-per-result). Fix the URL rather than retrying.
400	rejected	A parameter is missing or malformed: missing_parameter, invalid_cid, invalid_parameter or invalid_payout.
403	rejected	forbidden: wrong key, or a caller IP that isn't allowed.
503	rejected	no_snapshot: the server is starting up. Retry after the Retry-After header (60 seconds).

When a conversion is paid

An accepted conversion is paid once, and only when its click ID belongs to a scan of the same campaign within the campaign's attribution window (30 days unless the campaign sets another). A conversion with an unknown click ID, a click from another campaign or a click outside the window is recorded but not paid. Paused and ended campaigns keep accepting postbacks for the length of the window, so late conversions from earlier scans still count.

Sources

Checked on October 8, 2026. Parameter and macro names differ per platform and account; your platform's own documentation wins.

1. TUNE: How to use parameters, values and macros for tracking (aff_click_id, aff_sub to aff_sub5)
2. Scaleo: TUNE (HasOffers) integration (aff_click_id={click_id} on the TUNE link, {aff_click_id} in the postback)
3. Everflow: Your guide to parameters and macros (sub1 to sub10, sub1 commonly the partner's click ID)
4. CAKE: Understanding the CAKE tracking link (s1 for steady source values, s2 to s5 for unique ones)
5. CAKE: How to implement a TUNE (HasOffers) postback URL
6. Affise: Affise tracking link parameters (sub1 to sub8)
7. impact.com: Link parameters (subId1 to subId3)
8. AppsFlyer: Attribution link specification for ad networks (clickid)

Keep reading

• Pricing: fixed or reported payouts, and the attribution window.
• Stats: where accepted conversions show up.
• Ad policy: what ads and landing pages may and may not show.
• For advertisers: how SofAds campaigns work.