PartnerStack Postback Setup: The Complete Guide

PartnerStack is one of the most popular SaaS affiliate networks, and like most modern networks it supports S2S postbacks out of the box. Here's the end-to-end setup.

1. Where to configure it

As a partner, open Settings → Tracking. Look for the section labeled Postback URL or S2S tracking. You set one URL per reward event (signup, qualified lead, paid customer).

2. PartnerStack macros

• {partner_key} — your unique partner key. Useful for routing.
• {customer_key} — PartnerStack's unique customer ID. Great idempotency key.
• {reward_amount} — the commission amount.
• {reward_currency} — currency code.
• {custom_key} — the SubID you injected on landing (where your fbclid/gclid lives).

3. Putting it together

https://yourdomain.com/p?click_id={custom_key}&payout={reward_amount}&customer={customer_key}&currency={reward_currency}

4. Passing the click ID

PartnerStack's referral links accept a ?custom= query string. On your landing page, do:

const fbclid = new URL(location.href).searchParams.get("fbclid");
const link = "https://partnerstack.merchant.com/aff/yourcode?custom=" + encodeURIComponent(fbclid ?? "");

5. Test it

Send a test event from PartnerStack's tracking page. The macros will be replaced with sample values; confirm your endpoint receives them and logs the click ID you'd expect to see.

6. Forward to ad platforms

Once you have a real fbclid/gclid in custom_key, your forwarding endpoint can push it to Meta CAPI or Google Ads. See our CAPI guide for the exact payload.

Common pitfalls

• Forgetting to URL-encode custom. Special characters in fbclid break the postback.
• Configuring the postback on the wrong reward type — set it on the reward that actually pays you.
• Treating customer_key as the click ID. It's a customer identifier, not your click.