The state of desktop header bidding in Bulgaria in July 2019 – market analysis

Some of you may remember our header bidding market analysis we did for Poland in June 2019. This time we decided to investigate another important, fast-growing market – Bulgaria. The hypothesis stays the same: prebid.js-based header bidding has a positive impact on publishers automated sales and therefore they should be likely to implement it.


In order to conduct the analysis we used the same proprietary crawler as previously and scanned desktop websites against ads.txt and prebid.js. We fed it with a 208 domain list obtained from Gemius ranking for Bulgaria. Again, we cleared the list in order to remove search engines, social media and corporate websites as wanted to be 100% sure that the analysed sample consisted of publishers only. In practice, we only took into consideration domains our crawler reported as having implemented ads.txt file. As this tool was created for publishers only, everything that came without it was automatically filtered out. The final list included 125 desktop domains. Of course there might be publishers who do not use ads.txt yet, still we wanted to avoid false positives first.

Afterwards, we scanned the cleared list against prebid.js in order to verify how many domains already onboarded this header bidding standard. As a next step we analysed demand partners included in prebid.js files and ranked them according to their popularity. Since GAM is not prebid.js compliant, we also scanned websites against direct GAM implementation.

Results can be found below.


Around 60 % out of 208, ie. 125 analysed domains belong to publishers and not to other kind of business, which are out of scope of this analysis.


Found across 18% of top 125 publisher domains and across 48% of top 25 publisher domains.

Demand Partners/SSPs



The level of prebid.js adoption in Bulgaria is still relatively low given the potential of this solution. 18% is way less than in Poland, where it was 46%, not to mention almost 80% in the US. Similarly, bigger publishers are more likely to implement prebid.js, but again, the share is smaller – 48% of top 20% of publishers comparing to 75% of top 20% of publishers in Poland. While answering the question about the reason of such situation would require a more in-depth analysis, we can assume that:

  • Publishers in Bulgaria are less advanced in terms of programmatic in general;
  • Direct sales still dominate on this market;
  • Probably there is little body of knowledge on programmatic advertising available for local publishers on Bulgaria market.

What is not very surprising are the most popular SSPs competing for Bulgarian inventory available through header bidding, namely Google and Appnexus, and then Rubicon Project and Criteo. Apparently these companies have already done their homework in terms of satisfying the needs of CEE publishers. The most noticeable difference between Bulgaria and Poland is the position of Adform and OpenX – the former is very strong in Poland and not that strong in Bulgaria, whereas the latter is pretty strong in Bulgaria and less popular in Poland.

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