GNUnet is a comprehensive framework for building decentralized, privacy-preserving applications. It includes subsystems for routing, identity, file sharing, messaging, and payments, all designed with strong adversarial assumptions. Unlike single-purpose protocols, GNUnet aims to be a full alternative networking stack.

Its significance lies in its rigor. GNUnet treats surveillance, censorship, and centralization as default threats rather than edge cases. While complex and academically inclined, it serves as a reference point for what a principled, end-to-end decentralized infrastructure can look like.