Overview
Several major privacy and anonymity networks exist today, each with different design goals and threat models.
While Tor, Lokinet, GNUnet, and Freenet all contribute valuable approaches to privacy-preserving communication, I2P stands out as the only production-ready, packet-switched network fully optimized for in-network hidden services and peer-to-peer applications.
The table below summarizes key architectural and operational distinctions across these networks as of 2025.
Privacy Network Comparison (2025)
| Feature / Network | I2P | Tor | Lokinet | Freenet (Hyphanet) | GNUnet |
|---|---|---|---|---|---|
| Primary Focus | Hidden services, P2P applications | Clearnet anonymity via exits | Hybrid VPN + hidden services | Distributed storage & publishing | Research framework, F2F privacy |
| Architecture | Fully distributed, packet-switched | Centralized directory, circuit-switched | Packet-switched LLARP with blockchain coordination | DHT-based content routing | DHT & F2F topology (R5N) |
| Routing Model | Unidirectional tunnels (inbound/outbound) | Bidirectional circuits (3 hops) | Packet-switched over staked nodes | Key-based routing | Random walk + DHT hybrid |
| Directory / Peer Discovery | Distributed Kademlia netDB with floodfills | 9 hardcoded directory authorities | Blockchain + Oxen staking | Heuristic routing | Distributed hash routing (R5N) |
| Encryption | ECIES-X25519-AEAD-Ratchet (ChaCha20/Poly1305) | AES + RSA/ECDH | Curve25519/ChaCha20 | Custom symmetric encryption | Ed25519/Curve25519 |
| Participation Model | All routers route traffic (democratic) | Small relay subset, majority are clients | Only staked nodes | User-selectable trust mesh | Optional F2F restriction |
| Traffic Handling | Packet-switched, multi-path, load-balanced | Circuit-switched, fixed path per circuit | Packet-switched, incentivized | File chunk propagation | Message batching and proof-of-work |
| Garlic Routing | ✅ Yes (message bundling & tagging) | ❌ No | Partial (message batches) | ❌ No | ❌ No |
| Exit to Clearnet | Limited (discouraged) | Core design goal | Supported (VPN-style exits) | Not applicable | Not applicable |
| Built-In Apps | I2PSnark, I2PTunnel, SusiMail, I2PBote | Tor Browser, OnionShare | Lokinet GUI, SNApps | Freenet UI | GNUnet CLI tools |
| Performance | Optimized for internal services, 1–3s RTT | Optimized for exits, ~200–500ms RTT | Low latency, staked node QoS | High latency (minutes) | Experimental, inconsistent |
| Anonymity Set Size | ~55,000 active routers | Millions of daily users | <1,000 service nodes | Thousands (small core) | Hundreds (research only) |
| Scalability | Horizontal via floodfill rotation | Centralized bottleneck (directory) | Dependent on token economics | Limited by routing heuristics | Research-scale only |
| Funding Model | Volunteer-driven nonprofit | Major institutional grants | Crypto-incentivized (OXEN) | Volunteer community | Academic research |
| License / Codebase | Open source (Java/C++/Go) | Open source (C) | Open source (C++) | Open source (Java) | Open source (C) |
Why I2P Leads in Privacy-First Design
1. Packet Switching > Circuit Switching
Tor’s circuit-switched model binds traffic to fixed three-hop paths—efficient for browsing, but brittle for long-lived internal services.
I2P’s packet-switched tunnels send messages across multiple concurrent paths, automatically routing around congestion or failure for better uptime and load distribution.
2. Unidirectional Tunnels
I2P separates inbound and outbound traffic. This means each participant only ever sees half of a communication flow, making timing correlation attacks significantly harder.
Tor, Lokinet, and others use bidirectional circuits where requests and responses share the same path—simpler, but more traceable.
3. Fully Distributed netDB
Tor’s nine directory authorities define its network topology. I2P uses a self-organizing Kademlia DHT maintained by rotating floodfill routers, eliminating any central control points or coordination servers.
4. Garlic Routing and Bundling
I2P extends onion routing with garlic routing, bundling multiple encrypted messages into one container. This reduces metadata leakage and bandwidth overhead while improving efficiency for acknowledgment, data, and control messages.
5. Universal Participation
Every I2P router routes for others. There are no dedicated relay operators or privileged nodes—bandwidth and reliability automatically determine how much routing a node contributes.
This democratic approach builds resilience and scales naturally as the network grows.
6. Optimized for Hidden Services
I2P’s 12-hop round-trip (6 inbound + 6 outbound) creates stronger unlinkability than Tor’s 6-hop hidden service circuits.
Because both parties are internal, connections avoid the exit bottleneck entirely, providing faster internal hosting and native application integration (I2PSnark, I2PTunnel, I2PBote).
Architectural Takeaways
| Design Principle | I2P Advantage |
|---|---|
| Decentralization | No trusted authorities; netDB managed by floodfill peers |
| Traffic Separation | Unidirectional tunnels prevent request/response correlation |
| Adaptability | Packet-switching allows per-message load balancing |
| Efficiency | Garlic routing reduces metadata and increases throughput |
| Inclusiveness | All peers route traffic, strengthening anonymity set |
| Focus | Built specifically for hidden services and in-network communication |
When to Use Each Network
| Use Case | Recommended Network |
|---|---|
| Anonymous web browsing (clearnet access) | I2P |
| Anonymous hosting, P2P, or DApps | I2P |
| Anonymous file publishing and storage | Freenet (Hyphanet) |
| VPN-style private routing with staking | Lokinet |
| Academic experimentation and research | GNUnet |
Summary
I2P’s architecture is uniquely privacy-first—no directory servers, no blockchain dependencies, no centralized trust.
Its combination of unidirectional tunnels, packet-switched routing, garlic message bundling, and distributed peer discovery makes it the most technically advanced system for anonymous hosting and peer-to-peer communication today.
I2P is not “a Tor alternative.” It’s a different class of network—built for what happens inside the privacy network, not outside of it.