Tracking Pixel vs Postback URL: Which is Better for Conversion Attribution


Conversion Tracking Pixel


Pixel Tracking

Also called client-side, cookie-based, in-browser tracking. This method relies on the user’s browser to track conversions by placing a cookie on the click that is called again on conversion to authenticate the session and attribute the conversion to the correct affiliate. Pixel-based offers use cookies to track because they can store the session values in the cookie, and with the way pixels are designed to track, can extract this information from the browser easily. As a result, setting up an offer to track using pixels is very simple and only involves placing the HTML offer pixel on the conversion page.

Use pixel tracking when:

TUNE’s general recommendation is to use pixel tracking as little as possible, as pixel tracking only works for non-mobile web traffic where cookies can be stored. Additionally, major browsers like Safari, Chrome, and Firefox are moving away from allowing tracking-related cookies even for first parties.

As the last resort, use pixel tracking if the following are true:

The offer’s advertiser is unable to send server-side conversion notifications.
The offer does not involve mobile app installs.
The offer’s desired end users are on browsers that support tracking-related cookies.

Tracking Pixel, also known as browser-based or cookie-based, is a tracking method that allows users to track webpage visits, ad impressions, conversions, and other types of online activities.

A tracking pixel is an HTML piece of code that can be placed on a landing page or offer page to track the visitors’ actions.

In order to use tracking pixel for tracking conversions of your offers, you need to place the tracking pixel on a confirmation or a thank-you page.

When a user visits the confirmation page your tracker – e.g. Voluum – will be able to register a conversion for that specific ad and campaign specifically thanks to the tracking pixel code.

How? We are able to place and later read the cookie with a unique click ID value that identifies a user along the campaign funnel. This cookie is being placed in the user’s browser when the ad is displayed.

As you can see, tracking your offers with a tracking pixel is very straightforward and does not require a complex technical savvy. It’s simply placing a piece of code on the page right after a conversion happens. And the job is done.


  • A conversion tracking pixel is your ultimate solution when you don’t have many technical resources and you own the “thank you page” (meaning that you don’t buy media on behalf of any 3rd party);
  • It is simple and quick to implement, effortless to use, so you don’t need to be a tech expert – you can start tracking right away;
  • It is a matter of just copying the pixel from Voluum and pasting it into the code of the final thank you page that a user sees after the conversion has happened. Simple as that.


  • Occasionally, pixels might not fire. Why? One of the reasons could be that the user cleared their cache between clicking on a link on a landing page and the actual conversion. In that case, a conversion simply won’t be tracked.
  • Apple implemented Intelligent Tracking Protection 2.0 on Safari which prevents websites from being able to track users’ browsing habits without their permission. Right now, a website can request tracking privileges, but the user has to specifically opt-in. Even if the user agrees for tracking in Safari, unless they interact with that particular website over the period of 30 days all data and cookies will be permanently deleted. All in all, pixel tracking can get pretty difficult on Safari.
  • Additionally, Google announced that their web browser, Chrome, will stop supporting 3rd party cookies from 2022. This will also cause problems for pixel tracking.

Postback Tracking

Also known as server-side, server call, server 2 server (or server-to-server), s2s and, mistakenly, server pixel tracking, relies on the advertiser’s servers to track sessions generated on clicks to attribute conversions.  The servers record and then pass the transaction ID back to TUNE. This method is independent of the user’s browser. Postback tracking can be thought of as two separate processes: what happens when a user clicks on an offer and what happens upon conversion.

Leading up to the conversion:

  1. User sees an offer.
  2. User clicks on the offer.
  3. Click goes to a TUNE server. The server records the click, then generates and records the ID for that session (in most cases the transaction ID).
  4. TUNE immediately directs the user to the offer’s landing page, including ID for that session in the offer URL.
  5. User sees offer’s page on advertiser’s site. Advertiser’s site handles recording that session’s ID however it deems fit, such as storing it as a variable in an e-commerce site or SDK in a mobile app.

When the user converts on that offer:

  1. The advertiser’s server sends a signal to TUNE (a.k.a. fires a postback) that includes the ID TUNE initially supplied. The user is not directed back to TUNE in any way.
  2. TUNE records the conversion for that session.

Use postback tracking when:

You have the technical resources available to implement the server-side calls (see below for details on implementation).

Postback URL Tracking is also known as server-side or Server-to-Server (S2S) tracking. If you choose this method, a click ID value is generated and sent to your affiliate network via HTTP request.

Later, when a conversion happens, the affiliate network passes this value right back to Voluum. Once this action is completed, you see a conversion in your reports. Having received the value of click ID, Voluum is then able to recognize the exact visit and attribute the conversion to the right campaign.

Simple, right?


  • Using S2S postback URLs is more secure and reliable method to count conversions, thus it is highly recommended to use it whenever you can. Voluum creates unique S2S postback URLs for each account and supports only secure HTTPS format.
  • S2S postback URLs ensure accurate tracking and stats gathering. This type of tracking happens does not depend on cookies, so it works even if a visitor has cookies blocked on their web browser. For this reason, it is considered one of the most trusted tracking methods.


  • Postback tracking has to be supported by your affiliate network.
  • With other trackers, you would also have to set up appropriate parameters and tracking tokens to accurately pass information. Luckily Voluum has templates for all major affiliate networks that contain all parameters and tokens already set up an a psotback URL ready to submit to your affiliate network. You can earn more about postback URL tracking from our knowledge base.

Hey, what about the API method mentioned before?

That’s right, there is a third method of tracking conversions and it is based on the ad tracker’s API integration with an affiliate network.

This turns our competition into a three-way duel.

A truel.

This is the most reliable method of conversion tracking, as it happens at the back-end of both platforms. No messy tokens and parameters. When a conversion happens, the affiliate network’s infrastructure pings an ad tracker with all necessary information.

However, as this solution requires a lot of development work on both sides, it is not very prevalent in the affiliate marketing landscape.


  • The most reliable method of passing conversion, fool-proof and secure. Doesn’t need cookies to work.
  • It is a “set-and-forget” solution. Once you perform integration, you don’t have to set anything up, conversions will be passed on along with additional information, such as payout.


  • It is rarely used, as it requires a lot of effort to be implemented.

You will be glad to hear that Voluum uses the API integration for conversion tracking with Clickbank. Read the document that describes the Clickbank integration if you want to learn more.

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