The Xanadu Network

A docuverse of independent servers, connected by permanent, cryptographically verified, attribution-preserving references — the vision Ted Nelson had in 1960, working today.

The Vision

In 1960, Ted Nelson envisioned a universe of documents — a docuverse — where content could be connected, reused, and traced across independent servers. Not a web of pages, but a network of connections at the character level. Every quotation would maintain its bond to the original. Every reuse would carry its full provenance.

The World Wide Web (1989) gave us one-way links between pages. Nelson's Xanadu was different: bidirectional, typed, permanent connections between passages — with content staying on its origin server, never copied, always verified.

Xudanu implements this vision.

Two independent Xudanu servers connected by a tumbler reference. Content stays on its origin server; references travel between them.

What We Proved

On July 10, 2026, we verified the full cross-server pipeline end-to-end with two independent Xudanu servers running on separate ports with separate data directories:

No central registry was consulted. No shared database was synchronized. No federation protocol was used. Two sovereign servers discovered each other, exchanged a permanent reference, and shared verified content — exactly as Ted Nelson designed.

Tumbler Addressing

Every piece of content in the Xudanu network has a permanent, globally unique address called a tumbler. This is Nelson's innovation from the 1970s — a hierarchical, dotted notation that identifies content across servers.

A domain-based tumbler. The domain replaces Gold's numeric server IDs, enabling DNS self-routing.

The domain format ("alice.xudanu.com".03ed.1.0.0) is Xudanu's enhancement over Gold's original numeric format (1.03ed.1.0.0). DNS provides self-routing — no central registry needed.

Setting Up a Server

Any Xudanu server can join the network by publishing its identity and content.

./xudanu-server run 0.0.0.0:8080 data \
  --server-name "Alice's Literature Server" \
  --server-description "Essays and annotations" \
  --public-address alice.xudanu.com

curl https://alice.xudanu.com/.well-known/xudanu-server.json

curl https://alice.xudanu.com/api/public/work/03ed

Connecting Two Servers

Once two servers are running and have published content, users can create cross-server links:

Security Model

Cross-server content sharing uses three independent layers of verification:

Why HTTP is safe for content fetches

A man-in-the-middle cannot substitute different content because they would need to produce content with the exact same BLAKE3 hash — which would take 10²² years (longer than the age of the universe). The hash is stored at link creation time and verified on every fetch.

Additional protections

Adversarial resilience (v1.6.0)

Every document arriving from a peer passes a structure validation gate before it can touch server state: positions, spans, transclusion ranges, and provenance are checked against strict invariants, with size caps against resource exhaustion. Malformed entries are rejected individually and logged — the sync continues, the attacker's data does not. Identity responses are Ed25519-signed by the serving server and verified against the key registered in your directory, with a freshness window against replay. See Adversarial Resilience for the full method and findings.

Governance

Federation membership decisions (admit, expel, key rotation) are made by a PBFT consensus among 3–10 member servers: total ordering, Byzantine fault tolerance (f faulty members tolerated in 3f+1), no forks. A single compromised server cannot corrupt governance or rotate another server's keys — the quorum is required.

Operating a Server Safely

Server operators control the trust posture with run flags. The defaults are safe; the flags let you relax them deliberately.

Gold Heritage

This implementation inherits directly from the Udanax-Gold hypertext model (open-sourced 1999), with modern adaptations:

History: From 1960 to Today

The Xanadu project spans over six decades — one of the longest-running visions in computing history. Understanding this history helps explain why the cross-server network works the way it does, and why certain design decisions (tumblers, bidirectional links, content addressing) were worth the wait.

The Xanadu timeline: 39 years from vision to open source (1960–1999).

The Key Innovations (and who built them)

What Happened to Xanadu?

The Xanadu project faced many challenges over the decades:

• Complexity — the enfilade was a trade secret for 20 years, making collaboration difficult
• Funding — Autodesk dropped the project in 1992; programmers went unpaid in 1994
• The Web — Tim Berners-Lee's simpler one-way link model (1989) dominated while Xanadu was still unfinished
• Vision vs. execution — Nelson's vision was decades ahead, but the implementation kept being rewritten

But the ideas were sound. Ted Nelson's 1965 paper introduced concepts that the web still hasn't fully adopted 60 years later: bidirectional links, transclusion, and content addressing. The open-sourcing in 1999 allowed these ideas to survive and influence new implementations.

How Xudanu Carries the Torch

Xudanu is not a port of Udanax-Gold. It is a reimagining of Nelson's vision using modern technology, informed by the Gold codebase and its innovations:

Udanax-Gold vs. Xudanu: same vision, modern implementation.

The People

The Xanadu project involved many brilliant minds over the decades:

• Ted Nelson — the visionary. Coined "hypertext" and "hypermedia" (1965). Designed the docuverse, transclusion, and the principle of permanent, bidirectional connections. His 1960 vision drives Xudanu today.
• Mark Miller — architect of Udanax Gold (1992). Inventor of the Ent data structure and the General Enfilade Theory. Later went on to create the E programming language and work on secure distributed computing.
• Roger Gregory — co-inventor of the enfilade and tumblers. Key contributor during the Swarthmore summer (1978) that produced the foundational theory.
• K. Eric Drexler — inventor of the Ent (named after Tolkien's walking trees). Later became known as the father of nanotechnology.
• John Walker — founder of Autodesk. Backed the Xanadu project (1983–1992). Built the first transpointing windows demo (1988).
• Ka-Ping Yee — built PYXI (1999), the first working frontend over Udanax Green. His Declaration of Independence demo is the canonical Xanalogical visualization.