Chrome, Safari and Firefox all block third party cookies by default. If your tracking link is on yoursite.com but the thank you page lives on checkout.com, the browser will not send your cookie to the second domain. Anything that relies on the cookie alone quietly fails.
How WCT Solves It:
When a visitor clicks a tracking link, the plugin appends ?wct_click_id=123 to the destination URL. The recommended pixel snippets read that value straight from the URL and include it in the tracking request, so no cookie is needed at any point.
Pick The Right Approach For Your Setup:
- Same domain, where the tracking link and thank you page are on one site. Either the cookie or the URL works, and even the simple one line image pixel is fine.
- Cross domain, where they are different sites. Use the recommended pixel snippets that read wct_click_id with URLSearchParams. Do not use the simple image tag here.
- Multi step funnel, with several pages before the thank you page. The recommended snippets store the click ID in localStorage on the first page they run, so as long as the final thank you page carries the same snippet, attribution survives even if an intermediate page dropped the URL parameter.
- Server to server, where the payment platform posts back. Use the postback URL. It works regardless of cookies, domains or browser settings.
The Practical Checklist:
- Confirm the destination URL really does receive ?wct_click_id= after a click. Open the link in a private window and look at the address bar.
- Confirm the checkout or landing page does not strip query parameters. Many page builders and some carts do.
- Use the URLSearchParams pixel, not the one line image tag, on any page that is not on the same domain as your tracking link.
- If the platform strips parameters no matter what you do, stop fighting it and switch that platform to a server postback.
When Nothing Else Works:
If your checkout platform will not carry a parameter and will not fire a webhook, there is no reliable browser side workaround. In that situation, move the conversion event to a page you control, for example your own thank you page that the platform redirects to after purchase, and fire the pixel there.