Precision data and technology company 51Degrees is launching a new digital advertising identifier that effectively enables privacy-forward interoperability across the digital advertising supply chain. By putting the appropriate measures in place that ensure the identifier cannot be considered personal data, the 51Did promises to enhance consumer privacy, create a more efficient digital advertising supply chain, and allow Open Web businesses to compete with the platforms on a level playing field.

The 51Did works by embedding contractual terms into the identifier when it is shared with other authorised participants in the supply chain. When a user visits a publisher, the publisher creates a Match Key which expresses the user’s stated marketing preferences (standard or personalised). When this match key is shared with other market participants, the embedded contract prevents all legal means of re-identification of that individual. Because the recipient of the Match Key is not legally capable of re-identifying the user, it is not personal data under GDPR or US privacy laws for authorised recipients. Any breach of the contract would result in the offending party being banned from the scheme, publicly identified and reported to data protection authorities.

Sensitive data (racial or ethnic origin, political opinions, religious or philosophical beliefs, health, sex life or sexual orientation, genetic or biometric data, criminal history, or anything else classed as special category data) is excluded from the scheme entirely.

The 51Did is designed to overcome the increasingly complex limitations faced by the Open Web as a result of confused guidance about privacy regulation. The current system relies on the repeated collection of consent signals from consumers who are not meaningfully informed (or often don’t care) about the business processing purposes about which they are being asked. This consent structure doesn’t add to consumer privacy and primarily benefits the Big Tech platforms who are effectively exempt from it. The 51Did mitigates this consent fatigue by ensuring that data necessary for fraud detection, billing, measurement, and other advertising purposes passed through the advertising supply chain does not require additional popups.  

The 51Did also promises to add important new functionality to help strengthen the digital advertising supply chain. Because all participants in the 51Did chain are verified by 51Degrees, the original publisher is guaranteed to be who they say they are, instantly preventing huge swathes of advertising fraud. In addition, the ID includes creator context, which ensures that an ID is still being used in the same place that it was created, again preventing a significant vector for ad fraud.

The 51Did is intended to replace identifiers stored in cookies as a means of transmitting information across the advertising supply chain to enable key functionality such as measurement, attribution, anti-fraud controls and more. Because it is the first such ID to remove personal data from the equation whilst enabling these capabilities, it offers a new level of efficiency and effectiveness for the advertising supply chain.

51Did will be available for free for the first 12 months until October 2027.

James Rosewell, CEO of 51Degrees, said: "This has the potential to revolutionise the Open Web. For too long, the Open Web has been struggling under the weight of confusing privacy guidance that demands ever increasing complexity from rivals to big tech platforms. 51Did simplifies interoperability across the Open Web supply chain and therefore enables it to compete on a level playing field with the tech giants."

Olly Burns, CTO of Teal, said: "51Did is a truly innovative new approach to digital identifiers. By embedding the contractual terms within the ID and assuring compliance across the value chain the 51Did escapes the increasingly impenetrable thicket of privacy legislation and guidance that is strangling the Open Web. By removing the question of unmitigated risk from the supply chain 51Did enhances privacy whilst enabling publishers, advertisers, agencies, and ad tech to operate more efficiently and effectively."