dppvalidator is the "GDPR compliance engine" for physical products, enforcing the strict digital syntax required for the EU's Digital Product Passport.

EU Digital Product Passport for Biosphere Solar panels

Feasibility study: storing EU Digital Product Passports on Cardano

Local Optimization with Overflow Protocol (LOOP) — the open protocol specification for federated circular economy infrastructure. Defines how cities track, exchange, and settle materials and products across boundaries while maintaining local sovereignty.

Semantic vocabulary framework for Digital Product Passports — harmonising GS1, EU ESPR, UNTP, and CEN/CENELEC JTC 24 standards. Browsable ontologies at ref.openepcis.io.