The deprecation of third-party cookies is getting closer, and since the final release of the IAB Tech Lab’s SDA is already live, it’s time to get a grip around it.

Over the past months, the global rush to prepare for the upcoming deprecation of third-party cookies has only been heating up, making this one of the major digital trends for Q3 and Q4 2022

In this respect, most publishers of editorial inventory have been putting exceptional efforts into the upgrade of their first-party data strategy in order to maintain their viability as Supply partners in the eyes of their top-value direct and programmatic advertising partners. 

And now that IAB Tech Lab has presented the final iteration of its Seller Defined Audiences specification, it’s time they get a grip around its perks and downsides, as well as the specifics of its implementation. 

What are Seller Defined Audiences?

Simply put, Seller Defined Audiences (short: SDA) is known to be the IAB Tech Lab’s technical specification, which establishes the unified standard for creating audience segments and their further passing in the OpenRTB bid requests for advertisers’ bidding. 

Even though SDA was first introduced back in 2021, its final iteration hasn’t been released until February 2022, and the online advertising industry has been weighing how fast its adoption is going to go ever since. 

Why Publishers Need SDA

From a publishers’ perspective, the obvious benefits of implementing SDA include their ability to monetize top-quality first-party data efficiently in a transparent, yet secure manner, via the OpenRTB bidstream.

In addition, the fact that data clean rooms are using SDA and Prebid to determine overlapping audience segments and signal these to DSPs is what can make the monetization process even smoother. 

Another important benefit is publishers’ ability to sustain their reputation as a reliable Supply partner to premium advertisers, seeking new, efficient ways to target their potential customers in a cookie-less environment. 

How to Implement Seller Defined Audiences

First, publishers need to segment their first-party audience data according to the IAB Tech Lab’s Audience Taxonomy to make these correctly readable and identifiable by partners on the Demand side.

Namely, the audience data, either provided by readers themselves or otherwise obtained from their use of publishers’ digital properties is attributed to one or several of the 1600 segments, which fall under several key categories, including demographics, interests and purchase intent. 

Example: the audience segment ID 705 will imply a cohort of readers is interested in Technology & Computing, specifically in Virtual Reality.

The use of custom audience taxonomy is also possible, but this needs to be validated by the IAB Tech Lab team, too. 

Tip! The list of currently approved segment taxonomies is available for reference here.

As soon as publishers are ready with their audience segmentation, they will be able to assemble their first-party data on-page via SetConfig for passing in the oRTB bid request, using the three attributes of the Prebid’s “ortb2” object (all required):

  • (string) – defines the audience segment’s creator;
  • (integer) – defines the taxonomy utilized;
  • (string) – defines the particular audience segment ID/s.

Note! Multiple audience segment declarations may be included in a single config. 

Example (using it will yield no results):

pbjs.setConfig ({
          ortb2:  {         
              "user": {
                 "data": [
                     "name": "",
                     "ext": { "segtax": 6 },
                     "segment": [
                              { "id": "703" },
                              { "id": "705" }

Proof of publishers’ audience quality is made possible through labeling of the data using the Data Transparency Standard (DTS) requirements, which is then available for review by DSPs and other businesses on the Demand side in the IAB Tech Lab’s Transparency Center.

In addition, the latest SDA iteration also implies the ability to pass contextual segments in the OpenRTB bidstream, if necessary (via the object).

Tip! Dive into more technical details, regarding SDA in the IAB Tech Lab’s SDA implementation guide.