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Technology and tracking

Tracking pixel

Also called tracking pixel, conversion pixel, pixel.

Short answer

A tracking pixel is a small piece of code – originally an invisible 1×1 pixel image – on an order confirmation page. When the page loads, the pixel sends a call to the tracking server with the order ID, order value and the click ID to be credited.

Definition of Tracking pixel.

Technically, a tracking pixel is an image or script element that triggers an HTTP call to the tracking server when the page it sits on loads. The call carries parameters – order ID, order value, currency and the click ID that identifies the affiliate – and the server records them as a conversion. The name comes from the original form: a transparent 1×1 pixel image that no one could see, but which the browser still fetched from the server.

The pixel is the oldest and simplest method of conversion tracking in affiliate marketing: a piece of HTML on the order confirmation page, and the store is up and running. The simplicity is also the weakness. The pixel runs in the customer's browser, so an ad blocker, a tab closed too quickly or an error in the page's other scripts can stop the call from being sent – and then the sale is never recorded.

In modern setups, the pure pixel has been replaced by a tracking script that can read the click ID from the URL and store it during the visit, or by server-to-server tracking, where the store's system reports the sale directly, bypassing the browser. The name lives on: many still call all conversion tracking the pixel, whatever technique is actually in use.

How the pixel fits into the tracking chain

The chain starts at the click: the affiliate sends the user through a tracking link that records the click and gives it an ID. The user lands on the store, adds to basket and completes the purchase. On the receipt page, the pixel loads with the order's data and the click ID, and the tracking server can now link the sale to the right click and calculate the commission.

The order means the pixel is only the last link. If the click ID is missing – because it was never stored, or because the customer came back another way – the pixel still fires, but the conversion cannot be attributed to any affiliate.

Tracking pixel vs. tracking script

AspectTracking pixelTracking script
Forman image element that triggers an HTTP callJavaScript that runs logic on the page
Can read the click ID from the URLno – only what has been put into the call in advanceyes, and store it as first-party storage
Survives the visitno – it fires and is doneyes, the stored ID follows the customer to the purchase
Typical placementonly on the order confirmation pageon every page plus a conversion call on the receipt

The pixel reports the sale – the script makes sure there is a click ID to report it with in the first place.

How it goes wrong

  • 01

    The pixel never fires

    Ad blockers, privacy extensions and customers who close the receipt page before it has fully loaded stop the call in the browser. The sale exists in the store's system, but the tracking server never heard about it. Logging and monitoring are the only way to discover the gap.

  • 02

    Missing order data in the call

    A pixel without an order ID makes deduplication impossible, and without an order value a percentage rate cannot be calculated. Both parameters must be included in every call – otherwise the sales end up as disputes instead of commissions.

  • 03

    A pixel on a page that can be reloaded

    If the pixel sits on an order status page the customer can return to, it fires on every visit. Without deduplication on order ID, the same sale would count several times.

At Affilyflow

Tracking pixel in practice

Affilyflow receives conversions from pixel and tracking script on the same endpoint, and attribution is decided on our server based on the click ID the call carries – not in the browser. The same order ID can never count twice in the same program, and every tracking event is logged, including those that do not become sales.

Because pixel and script run in the browser, we monitor ourselves whether a store's tracking has stopped reporting – and say so, instead of letting sales disappear silently.

Frequently asked questions

How does a tracking pixel work in affiliate marketing?

The pixel sits on the store's order confirmation page. When the page loads after a purchase, it sends an HTTP call to the tracking server with order ID, order value and click ID. The server matches the click ID with the original click and records the conversion for the right affiliate.

Why is it called a pixel?

The name comes from the original technique: a transparent 1×1 pixel image. The image was invisible to the user, but the browser still fetched it from the tracking server, and the fetch itself served as a signal that the page had been shown.

Can a tracking pixel be blocked by ad blockers?

Yes. The pixel runs in the browser, and ad blockers and privacy tools can stop the call, as can a tab that is closed too quickly. That is why tracking events are logged, and why server-to-server tracking is more robust – it skips the browser entirely.

Does a tracking pixel require cookie consent?

The call itself is an ordinary HTTP request, but if the setup sets or reads cookies or other storage on the user's device, the consent rules apply. What matters is what is stored and read – not whether the technique is called a pixel.

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