Keeping attribution intact when checkout is on another domain
When a visitor moves from your site to a checkout on a different domain, the browser treats it as a new session with a new client ID, so the purchase gets attributed to a referral from your own site instead of to the campaign that paid for it. Cross-domain linking passes the identifiers in the URL and fixes the ordinary case. Server-side fixes the harder one, where the checkout domain isn't yours to instrument at all.
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Cross-domain checkout · what breaks
The situation, as it usually presents — Cross-domain checkout
- 01
Purchases attributed to your own domain as a referral
The signature symptom.
- 02
Paid campaigns showing traffic and no revenue
The conversion landed in another bucket.
- 03
A hosted checkout you can't add tags to
Common with payment providers and booking systems.
Cross-domain checkout · the fix
What changes — Cross-domain checkout
Session continuity across the domain hop
One visitor, one session.
Campaign credit landing on the campaign
Rather than on self-referral.
Purchase sourced from the order record
Where the checkout domain can't be instrumented.
Cross-domain checkout · architecture
Why this pattern keeps recurring — Cross-domain checkout
Domain hops break tracking for reasons that are structural to how browsers scope storage, so no amount of tag configuration inside one domain solves it.
- 1
Cookies are scoped per domain
The checkout domain cannot read the cookie your site set. It's not a fault; it's the security model.
- 2
A new client ID starts a new session
So the purchase belongs to a visitor who apparently arrived from your own homepage.
- 3
Redirects eat parameters
A shortener or a login bounce in the middle of the hop drops the linker silently.
- 4
Some checkouts can't be tagged at all
Hosted payment pages and booking platforms often allow nothing. Only server-side reaches those.
Cross-domain checkout · diagnose
How the root cause gets found — Cross-domain checkout
In this order. Each step rules out a class of cause, so the last one usually has a single explanation standing.
- 01
Check how much revenue is attributed to self-referral
The fastest signal.
- 02
Walk the hop and read the URL on arrival
Is the linker parameter there?
- 03
Follow every redirect in between
Each one can strip it.
- 04
Confirm referral exclusions are set
On both properties.
- 05
Establish whether the checkout domain can be tagged
Determines the fix.
Cross-domain checkout · prove
How the work is proven — Cross-domain checkout
Against the client's own records, not a dashboard turning green.
Source of truth
Backend order records with the original click ID attached
- Linker parameter confirmed present on arrival at the checkout domain.
- Self-referral revenue reduced to near zero.
- A live purchase walked end to end across both domains.
- Click ID confirmed persisting to the order record where server-side is used.
- Reconciled over a fully closed window, matched on ID rather than on totals.
- Payload evidence captured from real transactions and handed over.
- The same reconciliation repeated 30 days later.
Cross-domain checkout · free audit
What we check in the free audit
- Check how much revenue is attributed to self-referral
- Walk the hop and read the URL on arrival
- Follow every redirect in between
- Confirm referral exclusions are set
- Establish whether the checkout domain can be tagged
Checked against
Backend order records with the original click ID attached
Free30 minutesNo obligation
Cross-domain checkout · when not to buy
Why there are no client numbers on this page — Cross-domain checkout
Most agency case studies lead with a percentage. This one doesn't, and the reason is worth stating.
- We don't publish client results we can't substantiate. An audit of this site in August 2026 found named testimonials and before-and-after figures that had never been measured — all of it was removed, and nothing has replaced it that isn't checkable.
- The results that do exist belong to clients under agreement. Publishing anonymised numbers without their sign-off would be the same problem in a thinner disguise.
- What we will commit to in writing is 95%+ conversion accuracy and 8+ Meta Event Match Quality, reconciled against your own order records. That is checkable by you, which a case study percentage never is.
- For proof from actual clients, the video testimonials on the site are real people describing their own rebuild. That is the strongest evidence we have, and it isn't a number we wrote.
Cross-domain checkout · what we deliver
What the work involves — Cross-domain checkout
Both domains listed in cross-domain configuration
In every relevant container and property.
The linker parameter verified surviving the hop
In the URL on arrival, not just on departure.
Referral exclusions set
So your own domain stops counting as a source.
Server-side fallback where linking can't reach
Purchase from the order webhook with the original click ID.
Written guarantee
95%+ tracking accuracy
Measured against Backend order records with the original click ID attached. Miss it and we keep working at no cost.
Pricing
Pick the package that fits your ad spend
Browser-side starter
$400One-time fee · lifetime ownership
Repairs the fault in your existing browser-side setup and verifies it on a live transaction. Honest about its ceiling: it fixes this instance, not the class.
- Root cause fixed, not worked around
- Verified on a live transaction
- Reconciled against your own records
- Written handover
1st-party server-side
Recommended$800One-time fee · most popular
Removes the class of failure rather than this instance. Money events sent from your order records through a first-party container on your own subdomain, so the browser can no longer lose them.
- First-party server container on your own subdomain
- Money events from your order records, not the browser
- Deduplicated on a shared event ID at every destination
- First-party cookies beyond Safari's 7-day cap
- 95%+ accuracy and 8+ Meta EMQ, guaranteed in writing
Full 1st-party stack
$1,800One-time fee · lifetime ownership
Every paid channel server-side plus the offline loop, for advertisers whose spend makes an attribution leak more expensive than the build.
- Everything in 1st-party server-side
- Pinterest, Snapchat, Reddit and LinkedIn CAPI
- CRM and offline conversion loop
- Refunds reversed at every destination
- Monitoring so the next break surfaces in days
FAQ
Cross-domain checkout questions, answered
For a checkout you control, usually yes. For a hosted checkout you can't tag, no — the purchase has to come from the order record server-side.
Because the checkout domain saw a visitor arrive from your site with no prior session. That's the textbook symptom of a broken hop.
Yes. The click ID has to survive the hop too, or the platform can't attribute the conversion to the click it charged you for.
Test it specifically. Redirect chains and login bounces strip URL parameters routinely, and it's the cause people skip past.
Free · 30 min
Fix attribution across your checkout domain
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