Ad library

An ad library is a public, searchable database where political advertising publishers must store transparency information about political advertisements. It allows anyone to see who paid for an ad, how much was spent, who was targeted, and when the ad ran. Ad libraries help citizens, journalists, and researchers track political advertising and hold sponsors accountable.

Legal Basis

While Regulation 2024/900 does not use the term "ad library," it requires publishers to make transparency information "easily and directly accessible to the public" in a searchable repository:

"Publishers of political advertising shall ensure that, for each political advertisement published, a transparency notice is publicly available in a dedicated, searchable repository that is directly and easily accessible to the public through the online interface of the publisher."

— Article 10(1), Regulation (EU) 2024/900

Why It Matters

Ad libraries transform political advertising from hidden persuasion into transparent public information. They affect publishers of political ads—especially online platforms—who must build and maintain these repositories, and sponsors who must accept that their advertising spending and targeting choices will be visible to everyone.

For citizens, ad libraries provide a window into political campaigns. You can see which parties are spending money to reach voters, what messages they're pushing, and whether they're using personal data to target specific groups. Journalists and researchers use ad libraries to investigate campaign spending, detect disinformation campaigns, and identify foreign interference in elections. Civil society organisations rely on them to monitor compliance with electoral finance rules.

The transparency requirement creates accountability. When political actors know their advertising will be publicly documented, they may reconsider deceptive or manipulative tactics. Ad libraries also help data protection authorities and media regulators enforce rules on targeting and transparency, making it easier to spot violations and take action.

Key Points

Mandatory for all publishers: Any entity that publishes political advertising—online platforms, newspapers, broadcasters, influencers—must maintain an ad library if they accept payment for political ads
Searchable and accessible: The repository must be easy to find, searchable by sponsor name, date, and other criteria, and free for anyone to access without login or payment
Comprehensive information: Each entry must show the sponsor, amount paid, targeting criteria, reach, publication dates, and a copy of the ad itself
Retention period: Information must remain in the ad library for at least five years after publication to enable long-term research and accountability
Cross-border visibility: Ad libraries help track political advertising across Member States, making it easier to spot coordinated campaigns or foreign interference
Enforcement tool: Regulators and civil society use ad libraries to verify compliance with transparency rules and identify violations

Ad library vs. Transparency notice

A transparency notice is the label that appears on each individual political advertisement, telling viewers it's a political ad and providing basic information. An ad library is the central database where all transparency information is collected and made searchable. Think of the transparency notice as the label on a single product, while the ad library is the warehouse inventory system that tracks every product. The notice appears with the ad when you see it; the library is where you go to research ads after they've run or to find ads you never saw yourself.

Aspect	Transparency notice	Ad library
Location	On the ad itself	Separate public repository
Purpose	Immediate identification	Research and accountability
Content	Basic sponsor info	Full campaign data and metrics
Audience	Ad viewer	General public, researchers

Related Terms

Political advertising
Publisher
Sponsor
Transparency notice
Targeting techniques
Provider of political advertising services
Online platform
Searchable repository
Media authority
Data protection authority

Very transparent. Every political ad will be labelled, linked to a transparency notice with detailed information, and online ads will be searchable in a central European repository.

The Network coordinates election-related cooperation between member states. National contact points for TTPA enforcement should be members of this network where possible.

Election campaigns will need to ensure all paid advertising includes proper labels and transparency notices. Sponsors must be prepared to provide required information to all service providers.

Several major platforms currently do not allow paid political advertising, including some large social networks. This limits where political actors can place paid online advertisements.

The TTPA applies from 10 October 2025. Member States had until 10 April 2025 to designate competent authorities, and the Commission must provide label templates by 10 July 2025.

Publishers must ensure completeness and accuracy of certain information but are not required to verify all sponsor claims. They must correct manifestly erroneous information when they become aware of it.

Yes. When a hosting provider and a website both display an ad, both are considered publishers with responsibility for their specific services. Contracts should clarify how they share compliance duties.

If a publisher removes or disables access to a political ad due to illegality or terms violations, they must still provide access to the transparency information for the full seven-year retention period.