The EU is asking how big platforms' public ad libraries should work, with guidelines planned for 2028

The European Commission opened a call for evidence on November 4, 2026, on how the public advertising libraries of the largest online platforms and search engines should work. It closes on December 2. The responses will feed technical guidelines that the Commission plans to publish in the second quarter of 2028, after a targeted public consultation on a draft in 2027.

The libraries are already required. Article 39 of the Digital Services Act obliges very large online platforms and search engines to keep public repositories, commonly known as ad libraries, showing each ad's content, who paid for it, when it ran, how many users it reached and the main criteria used to choose them. The Commission says the guidelines will advise on search, on insight into how users are targeted and reached, and on access to the content of ads.

What the Commission has already asked platforms to fix

The X decision was the Commission's first non-compliance decision under the law. The decision divides the €120 million into €35 million for the repository, €45 million for the blue checkmark and €40 million for researchers' access to data. A later Commission overview page gives €45 million for the repository, but the decision assigns that amount to the checkmark. The Commission's July account says X's plan will move search results onto the repository's own interface instead of separate Excel files and cut a response time of 200 seconds to the minimum technically achievable. X has six months to carry out the plan, followed by an independent audit. The Board for Digital Services, which the Commission consulted, found the proposed changes partially adequate but X's audit measures, and so the plan overall, insufficient. The Commission says it has clarified points X must consider in carrying out the plan.

X's side appears in the decision. It argued that the Commission had not given the guidance on repositories that Article 39(3) envisages, leaving platforms to interpret the duty themselves, and it cited an independent audit that found it compliant. The Commission answered that Article 39(3) allows guidelines but does not require them, and that an audit does not stop it reaching its own finding. A court fight is under way too: at the Commission's September 25 midday briefing, a reporter asked about the ongoing appeal at the EU's General Court, and the spokesperson said the Commission was “absolutely ready to defend its position in court.” The Commission's July pages carry no statement from X. TikTok's position appears through its commitments, which the Commission says address all of its concerns. In its May 2025 findings, the Commission said its preliminary view did not prejudge the outcome of the investigation.

Who would be covered

The Commission's supervision list, updated on October 28, shows 28 active designated services, 25 platforms and 3 search engines (our count, leaving out Stripchat, whose designation ended). The “very large” label applies above 45 million monthly users in the EU. The list gives average monthly active users as reported by the providers: 416.6 million for YouTube, 259 million each for Facebook and Instagram, 135.9 million for TikTok, 115.1 million for X, 102 million for Snapchat, 57.2 million for Reddit and 46.6 million for Roblox. ChatGPT, at 159.1 million, is listed as a search engine. So the guidelines would reach game and community services as well as the largest social networks (our reading).

Why the Commission wants it

The Commission argues that transparency about who pays and how people are targeted protects public health, consumers and the integrity of elections. It says repositories let researchers, journalists, civil society groups and national authorities spot risks such as scams, disinformation, deceptive selling and ads for illegal goods.

Our reading is that the specifics in the TikTok and X cases, such as 24-hour updates and API access, were settled platform by platform, and that guidelines could turn expectations like those into a common reference. The Commission says only that the guidelines will support its supervision and enforcement of Article 39. It has invited responses from researchers, civil society groups, journalists, platform and search providers and the advertising industry. Details are on its consultation page.