I2P

P2P Infrastructure

The Invisible Internet Project — an anonymous, censorship-resistant overlay network layer implementing garlic routing (a variant of onion routing). Every I2P router participates in routing for others, using unidirectional tunnel pairs and a distributed Kademlia DHT network database. Designed for internal darknet communication (.i2p sites, email, torrents) rather than clearnet outproxying.

Fully P2P Community Low capture risk
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Details

License BSD / Public Domain
Dev Status Released
Owner I2P Project (volunteer collective, largely pseudonymous developers) / StormyCloud Inc. (supporting infrastructure since 2025)
Country International
Start Year 2003
Stack Java, C, multiple language bindings
Funding Donations
Last Investigated Mar 10, 2026

Use Case Domains

Platform Evolution & Sovereignty Communication

Affordances

Self-hostable End-to-end encrypted

P2P Infrastructure Attributes

P2P Architecture Garlic routing (unidirectional tunnel pairs; packet-switched; multiple messages bundled per garlic); Kademlia DHT for peer discovery
Overlay Network Global (self-organizing network database; no central directory servers; rotating floodfill routers maintain netDb)
Content Addressing No (router-identity-addressed, not content-addressed; application-layer content addressing possible)
Local-First N/A (routing infrastructure; data transits encrypted tunnels, not stored at network layer)
E2EE Yes — three layers: garlic encryption (message delivery verification), tunnel encryption, inter-router transport encryption
Byzantine Fault Tolerance No (reputation-based peer selection; no Byzantine fault tolerant consensus)
Signature ElGamal/ECIES (encryption); Ed25519/DSA (signatures); X25519 (key exchange in ECIES-X25519 mode)
Permissions N/A (open routing; all I2P routers contribute to network)
Infrastructure Function Anonymous routing; Censorship circumvention (internal darknet focus)
Threat Model Mass surveillance; Traffic analysis; Targeted surveillance; Metadata exposure
Volunteer / Node Model Volunteer-operated (every I2P router automatically routes for others; no dedicated relay class)
Traffic Visibility No content (three-layer encryption); No metadata (unidirectional tunnels mean each router sees only previous/next hop)
Active Deployment Scale ~55,000 router nodes worldwide (Wikipedia/research, as of 2024-2025)