Cardano, Reef Data to let users sell pooled personal data

Cardano Foundation and Reef Data eG announced on July 28 a partnership to let cooperative members pool personal data, license datasets to businesses and record royalty payments on Cardano. The initiative lists Hamburger Volksbank, ARIC, VALIO and Disruptive Elements as backers.

Reef plans to gather members’ personal information into a cooperative pool. Members will be asked to request their own data from companies under the EU Data Act, review and anonymize it on their phones, and then contribute consented records. Reef states that the underlying personal data will be stored off-chain.

Cardano’s Reeve system will serve as the accounting layer for the cooperative. Reeve will log dataset sales, timestamp royalty payments, cryptographically anchor records and make distributions auditable on the Cardano ledger.

European rules for data intermediaries apply to the effort. The EU Data Governance Act requires recognized providers to register with national authorities and appear in a public registry. That registry was updated on July 28 and lists 36 providers across 10 countries; Germany’s only listed entry is Law & Innovation Technology GmbH, trading as Consenter. Reef has not announced whether it will seek registration.

The EU Data Act, effective since September 2025, focuses on data from connected devices such as cars and industrial machinery. The General Data Protection Regulation gives individuals a right of access to data companies hold (Article 15) and a right to data portability in a machine-readable format (Article 20). The partnership’s design may rely on rights provided by one or both laws.

The European Data Protection Board published guidance on July 7 recommending personal data be kept off-chain where possible because immutable ledgers can conflict with rights such as erasure and correction. Reef’s described architecture-on-device anonymization, off-chain storage and only sales and payment records on Cardano-matches that recommendation. Reef has provided limited technical detail about its anonymization process.

A technical and regulatory question is whether on-device processing produces true anonymization or only pseudonymization. Under EU rules, pseudonymized data still counts as personal information if it can be re-identified with additional information. Regulators may treat contributions as personal data until Reef publishes more detail.

Payout sizes will depend on buyer demand, dataset pricing and cooperative membership. Reef’s case study projects a global market rising from about $3.95 billion in 2025 to $19.32 billion by 2032. Independent market estimates place the organized data marketplace niche at roughly $1.5 billion in 2024.

Reef’s internal scenarios show a wide range. In a conservative example, 25 buyers sign two $5,000 contracts each, with a 50% royalty share split among 100,000 active members, producing about $1.25 per member per year. In a more optimistic example, 500 buyers sign four $50,000 contracts each, with a 60% royalty share split across 2 million members, producing about $30 per member per year.

Other data cooperatives prioritize different goals, including member-governed research access or direct consumer rewards. Reef’s proposal centers on commercial sales of consented datasets combined with an auditable ledger that records sales and royalty calculations.

The public ledger on Cardano will show whether dataset sales occurred and whether distributions followed published rules. Reef’s announcement did not include full technical specifications for anonymization or a statement on registration under the Data Governance Act. The partnership was announced on July 28 and names the listed institutional backers.