Summary
Key Findings:
- The biggest gaps across platforms concern user interface, search functionality, and information on ad performance.
- Existing ad libraries differ widely in how they implement DSA transparency requirements.
- Meta currently provides the strongest baseline, while platforms such as X, AliExpress, and Amazon show particularly serious shortcomings.
We assess and compare the current state of advertising library implementation across a range of platforms in light of Article 39 DSA, which requires publicly accessible ad libraries that include, for example:
- Content: Including the name of the product, service or brand
- Advertiser: The advertiser and the natural/legal person who paid for the advertisement
- Target metrics: If the ad targets specific audiences and the main targeting parameters used
- Recipients reached: The total number of recipients reached
Our findings show that implementation remains highly uneven across platforms. Additionally, it becomes clear that formal compliance alone is not enough. If ad libraries are to support transparency, accountability, and the monitoring of harmful or illegal advertising, they must be searchable, understandable, and genuinely usable in practice.
Across platforms, the main weaknesses concern user interface, search functionality, and transparency around ad performance metrics. In many cases, metrics about recipients reached are difficult to access, insufficiently explained, and therefore not comparable across services. Some ad libraries also fail to provide meaningful information on targeting criteria or advertiser identity. Particularly serious shortcomings can be seen in services such as X, AliExpress, and Amazon, where access, usability, or the level of detail fall far short of the DSA requirements. Meta currently offers the most comprehensive ad library and has laid important groundwork, but even there significant limitations remain, including API access restrictions, inconsistencies between visible ads and search results, and weaknesses in navigation and filtering.
Recommendations
Improve search and filtering functionality: Ad libraries should allow users to search by both keyword and advertiser, and to filter and sort results
Make key metrics understandable and comparable: Platforms should provide clear, standardized information on key metrics as well as tooltips or links next to reach, impression, and other performance figures, explaining what they mean and how they're calculated.
Platform Compliance Study (PCS) — funded by Kiras Sicherheitsforschung, Bundesministerium Finanzen, and Bundesministerium Arbeit, Soziales, Gesundheit, Pflege und Konsumentenschutz.
This research was conducted as part of the " Platform Compliance Study" project and funded by the Austrian security research programme KIRAS of the Federal Ministry of Finance (BMF).
