Transparency and data sharing in philanthropy: towards a data commons

Philanthropic data remains fragmented across organisations, jurisdictions, and reporting systems, limiting transparency, learning, and coordination. Drawing on interdisciplinary discussions from the ERNOP SafeSpaces 2025 roundtable, we examine data-sharing barriers and existing initiatives, identifying lessons and opportunities for future data infrastructures. Building on these, we derive design principles for an Open Philanthropy Data Commons: input flexibility, AI assistance, interoperability, and federated governance. Finally, we suggest an operational pipeline for implementation and close formulating further directions.