On 4 November 2026, the European Commission opened a call for evidence (running until 2 December 2026) on upcoming technical guidelines for the advertising repositories („ad libraries“) that very large online platforms and search engines must maintain under Article 39(3) of the Digital Services Act. The guidelines are to advise on how repositories can be made easily searchable, how insights into targeting and reach can be provided, and how the content of advertisements can be made accessible. A targeted consultation on the draft will follow in 2027; publication is planned for the second quarter of 2028.

1. Guidelines overdue, timetable too long

The repository obligations have applied since August 2023 – for three years, enforcement has taken place without a yardstick: a fine here, binding commitments there, every platform a special case. Non-compliance has already been sanctioned in individual proceedings (the EUR 45 million fine against X for its non-compliant advertising repository; TikTok’s binding commitments of 5 December 2025). Even TikTok itself criticised that guidance was being delivered through preliminary findings rather than clear, public guidelines. Guidelines arriving in Q2 2028 would mean five years of obligations without binding functional criteria. What is needed are binding interim benchmarks – searchability, completeness, timeliness – that can be benchmarked and independently measured. Deadlines do not protect; structure protects.

2. Searchability as a measurable criterion, not a claim

The guidelines must define minimum requirements: multi-criteria search across all mandatory fields (the party on whose behalf the advertisement was presented, the payer, the period, the targeting parameters, reach per Member State), an open API without registration hurdles, complete data records (creative content including destination URLs, not placeholders), and publication of fresh entries within 24 hours – the TikTok commitments show that all of this is achievable. The door to participation must not stand behind a door to identity verification – neither for researchers, nor for civil society, nor for citizens without an institutional budget.

3. One data structure instead of 25 incompatible archives

Every platform currently builds its own format; anyone who wants to examine advertising across Europe has to learn 25 interfaces. For political advertising, a common data structure with standardised metadata and API logic already exists (Implementing Regulation (EU) 2026/818). The same standard logic must be transferred to the DSA advertising repositories so that cross-cutting analyses – scams, disinformation campaigns, misleading commercial practices – become possible in the first place.

4. Transparency of advertising, not of people

Article 39(1) of the DSA rightly prohibits personal data of the recipients to whom an advertisement was or could have been presented – the guidelines must operationalise this: evaluation and researcher access without recipient profiles, no correlation identifiers across platform boundaries – interoperability is not linkability. And: removals and deletions in the repository under Article 39(3) must remain traceable and logged – whoever audits must be auditable themselves – otherwise a transparency hole opens up precisely for the most problematic content.

5. Participation instead of an expert tool

Advertising repositories are public instruments of scrutiny, not tools for a small circle of vetted researchers. Search interfaces must be multilingual and usable by citizens without programming skills – participation instead of instruction.

6. The archive shows the advertising, not the structure

A repository reveals who paid and who was meant to be reached – it does not measure how recommender systems amplify advertising and organic content. This amplification must be named in the guidelines as a separate, measurable risk point; otherwise transparency stops at the cheque and never reaches the system. Whoever sells attention also sells the conflict – the structural answer to that (categories instead of profile feeds) must be pursued beyond the advertising repository.