The online ad is getting a public receipt

The online advert used to disappear almost as quickly as it arrived. A discount video, a political message, a dubious health product or a glossy app promotion could flash through a feed, be targeted to a narrow audience, and leave little trace for anyone outside the campaign room.

That is the part of platform advertising now under pressure. Europe’s Digital Services Act does not abolish targeted ads, and it does not make every advert honest. What it does is make opacity harder to defend. The European Commission says ads must be clearly labelled and include information such as who placed them and why a person is seeing them. Very large online platforms also have to store ad information in a publicly accessible repository.

The dry phrase matters. A repository turns an advert from a private platform moment into a record that can be searched, compared and questioned. It gives regulators, researchers, journalists and civil society a way to ask whether scams are being pushed, whether age-inappropriate products are appearing in front of minors, whether election messages are being micro-targeted, or whether the same advertiser is showing different claims to different groups.

TikTok has become the useful example because the European Commission accepted binding commitments from the platform on advertising transparency under the DSA. The Commission said the commitments address concerns raised in its investigation and preliminary findings from May 2025. They include providing the full content of an advertisement as it appears in users’ feeds, including URLs in the ad, updating the repository more quickly so information is available within a maximum of 24 hours, publishing targeting criteria selected by advertisers, and adding aggregated reach data such as gender, age group and Member State.

The legal summary on EUR-Lex makes the point more sharply. The Commission decision makes TikTok’s commitments binding for five years. The case concerned the DSA obligation for very large online platforms to maintain and publish a searchable advertisement repository. TikTok did not acknowledge an infringement, but the decision still shows how regulators want these libraries to work: searchable, timely, complete enough to inspect, and useful beyond the platform’s own public relations page.

For ordinary users, this will not feel like a new app feature every day. The visible change is smaller. The ad in the feed should carry clearer information about why it appeared. A suspicious campaign should be easier to look up. A public-interest group should be able to examine patterns rather than rely on screenshots from people who happened to see the same advert. A researcher should be able to ask whether certain messages were aimed at particular age bands or locations.

That does not mean the public receipt is perfect. Ad libraries can be awkward to search. Data can be delayed, partial or difficult to interpret. Advertiser names can be messy. A person may still need context to understand whether a campaign is misleading or merely badly targeted. Platform libraries also vary, and the DSA’s strongest repository duties apply to very large services rather than every small site that sells an ad slot.

There is also a risk of mistaking transparency for accountability. Publishing a record is not the same as preventing a bad advert from running. The Commission’s own description says repositories are critical for detecting scams, illegal or age-inappropriate products, fake advertisements and coordinated information operations. Detection is necessary, but it is not the end of the chain. Someone still has to investigate, enforce rules, remove bad campaigns and explain what happened.

The more interesting shift is cultural. The personalised feed trained people to treat adverts as private interruptions: this one appeared to me, then vanished. A public repository treats them as part of the public digital environment. If a platform profits from targeted persuasion, the record of that persuasion should not belong only to the platform and the buyer.

That is why ad transparency is a technology story, not just a Brussels compliance story. The design of an ad library decides whether transparency is usable. Search filters, export tools, timestamps, targeting summaries, reach ranges and access for researchers are product decisions. So are the trade-offs around privacy, security and avoiding the publication of data that could identify individual users.

The next test is whether these systems become legible enough for people outside specialist policy circles. A useful ad receipt does not need to turn every user into an investigator. It needs to make the basics easier to see: who paid, what was shown, where it ran, who it tried to reach, and whether the platform changed or removed it later.

If that becomes normal, the online advert will still be persuasive, sometimes irritating and often forgettable. But it will be less ghostly. The feed may remain personalised, but the paper trail will be harder to keep private.