I2P (Invisible Internet Project)

I2P, the Invisible Internet Project, is a free, open-source anonymity network built as a self-contained overlay on top of the regular internet. Where Tor is oriented toward anonymously reaching the public web through exit relays, I2P is designed primarily for anonymous services that live entirely inside the network — analogous to Tor's onion services, but as the default mode rather than a special case. For a sovereign operator, it is best understood as a parallel anonymity layer with different strengths, different weaknesses, and — crucially — different failure modes.

Garlic routing and unidirectional tunnels

I2P uses a variant of onion routing called garlic routing. Instead of encrypting a single message in layers, it can bundle several messages ("cloves") together inside one encrypted package, which complicates traffic analysis by decoupling what enters a router from what leaves it. Its tunnels are also unidirectional: data travels to a destination along one path and returns along a different one, each built and rotated independently. Because the outbound and inbound paths differ, an observer who watches one direction learns less about the full conversation than they would on a bidirectional circuit. Tunnels are short-lived by design and rebuilt frequently, trading some latency and connection-setup cost for a moving target.

A fully peer-to-peer architecture

I2P has no directory authorities and no fixed relay hierarchy — every participant typically also relays traffic for others, and the network database that maps destinations to tunnels is itself distributed. This strengthens the network as it grows and avoids a small set of well-known exit points to pressure or block. The same design explains its natural fit: long-lived hidden services ("eepsites"), peer-to-peer file sharing, and distributed applications thrive inside I2P, while casually browsing the ordinary web is a weak fit, since outproxies — its equivalent of exit nodes — are few and not the network's focus. In the Bitcoin world this is not academic: Bitcoin Core supports I2P as a peer-to-peer transport alongside Tor, so a node can maintain connections over both networks at once — giving your node a second, independent anonymous path that keeps working even if one overlay is blocked or degraded.

Where it fits in a sovereign stack

The honest framing is redundancy, not replacement. Tor has the larger network, more research scrutiny, and far better usability for reaching the clearnet; I2P offers a structurally different design — peer-to-peer, unidirectional, service-first — that is valuable precisely because it fails differently. An operator who runs a node reachable over clearnet, Tor, and I2P has removed several single points of failure from their connectivity, the same layered thinking that leads people to pair internet infrastructure with Nostr for communications or Meshtastic for off-grid messaging. As with every privacy tool, the right choice depends on what you are defending against — there is no anonymity network that is best for everyone, only one that is best for your situation. That reasoning belongs in an explicit threat model, and the broader context lives in our sovereignty section.

Getting started realistically

Running I2P is a modest commitment: install the router software (the original Java implementation or the lighter C++ i2pd), let it integrate into the network for a few hours, and expect a different rhythm from Tor — first connections to a destination are slower while tunnels build, and the network rewards long-running routers over ones toggled on for five minutes. For Bitcoin specifically, enabling the I2P transport in your node's configuration alongside Tor costs little and adds a genuinely independent path. As always, anonymity networks protect traffic, not behaviour: an account name reused across networks links you faster than any protocol weakness. Start with low-stakes uses, learn how the network behaves, and add it to your stack because you understand it — not because a checklist said to.

Compare with Tor (The Onion Router) and Onion Service (.onion), and weigh which network fits your needs using a clear Threat Model.