S2S Postback Setup: A 5-Minute Guide for Affiliates

From zero to tracking real conversions. No SDK, no JavaScript — just a server-to-server postback URL and a few parameters.

What Is an S2S Postback?

A server-to-server (S2S) postback is a way for an affiliate network or advertiser to notify your tracker that a conversion happened — without relying on JavaScript pixels or iframes. The network sends an HTTP request directly to your tracker's postback URL with conversion data.

This is the gold standard for conversion tracking because it's reliable (no ad blockers can block it), fast (sub-second delivery), and flexible (you can pass any parameters).

How It Works

The flow is simple:

1. A user clicks your affiliate link → Xpnsr Tracker logs the click and redirects to the offer
2. The user converts on the advertiser's site (sale, lead, install, etc.)
3. The advertiser's server sends a POST/GET request to your postback URL with the transaction ID and payout
4. Xpnsr Tracker matches the conversion to the original click and updates your stats

Setting Up in Xpnsr Tracker

Step 1: Get your postback URL

In your Xpnsr Tracker dashboard, go to Settings → Postback. Copy your unique postback URL. It will look something like:

Step 2: Map macros

Each affiliate network uses different macro names. Common ones:

• {clickid} — the unique click ID (sometimes called {aff_sub}, {transaction_id}, {sid})
• {payout} — the commission amount ({amount}, {commission}, {payout})
• {status} — conversion status ({status}, {conv_status})

Map your network's macros to Xpnsr's parameters in the postback settings.

Step 3: Add the postback to your network

Paste the postback URL into your affiliate network's postback or callback settings. Most networks have a field called "Postback URL" or "Server Callback URL."

Testing Your Postback

Xpnsr Tracker includes a built-in postback tester. Navigate to Tools → Postback Tester, enter a test click ID, and click "Simulate Conversion." If the postback is configured correctly, you'll see the conversion appear in your dashboard within seconds.

Troubleshooting Common Issues

• No conversions showing: Check that your postback URL is correctly entered in the network's settings. Verify macro names match exactly.
• Wrong payout amounts: Ensure the payout parameter is being passed as a number, not a string with a currency symbol.
• Duplicate conversions: Some networks send multiple postbacks for the same conversion. Enable Xpnsr's deduplication in Settings → Postback.
• Timeouts: If your network reports timeouts, check that your postback URL is accessible from their servers (not blocked by a firewall).